阅读说明：本技术 用于通信系统中的原位串扰测量的方法和系统 (Method and system for in-situ crosstalk measurement in a communication system ) 是由 佩塔尔·伊万诺夫·克罗特涅夫 戴維德·图涅托 马克-安德烈·拉克鲁瓦 于 2020-02-29 设计创作，主要内容包括：一种方法包括去激活与连接到多信道通信架构的端点关联的第一多个收发器的多个发射器。所述第一多个收发器中的特定收发器包括接收器。所述方法包括控制所述特定收发器以使得所述特定收发器：将所述特定收发器的参考源耦合到所述接收器的第一节点,测量所述接收器的第二节点处的第一值,并根据所述测量到的第一值确定所述第一节点与所述第二节点之间的增益。所述方法包括：控制所述特定收发器以使得所述特定收发器将所述参考源与所述接收器的所述第一节点隔离；所述特定收发器测量所述第二节点处的第二值,并且所述特定收发器根据所述测量到的第二值确定固有噪声。所述方法包括：激活所述去激活的多个发射器；所述特定收发器测量所述第二节点处的第三值,并且所述特定收发器根据所述测量到的第三值确定复合噪声；所述特定收发器根据所述确定的增益、所述确定的固有噪声和所述确定的复合噪声,确定所述接收器的所述第一节点处的串扰噪声。(A method includes deactivating a plurality of transmitters of a first plurality of transceivers associated with an endpoint connected to a multi-channel communication architecture. A particular transceiver of the first plurality of transceivers includes a receiver. The method includes controlling the particular transceiver to cause the particular transceiver to: coupling a reference source of the particular transceiver to a first node of the receiver, measuring a first value at a second node of the receiver, and determining a gain between the first node and the second node from the measured first value. The method comprises the following steps: controlling the particular transceiver such that the particular transceiver isolates the reference source from the first node of the receiver; the particular transceiver measures a second value at the second node, and the particular transceiver determines the noise floor from the measured second value. The method comprises the following steps: activating the deactivated plurality of transmitters; the particular transceiver measuring a third value at the second node, and the particular transceiver determining a composite noise from the measured third value; the particular transceiver determines crosstalk noise at the first node of the receiver as a function of the determined gain, the determined intrinsic noise, and the determined composite noise.)

1. A method, characterized in that the method comprises:

deactivating a plurality of transmitters of a first plurality of transceivers associated with endpoints connected to a multi-channel communication architecture, wherein a particular transceiver of the first plurality of transceivers comprises a receiver;

controlling the particular transceiver to cause the particular transceiver to: coupling a reference source of the particular transceiver to a first node of the receiver, measuring a first value at a second node of the receiver, and determining a gain between the first node and the second node from the measured first value;

controlling the particular transceiver such that the particular transceiver isolates the reference source from the first node of the receiver;

the particular transceiver measuring a second value at the second node, and the particular transceiver determining the noise floor from the measured second value;

activating the deactivated plurality of transmitters;

the particular transceiver measuring a third value at the second node, and the particular transceiver determining a composite noise from the measured third value;

the particular transceiver determines crosstalk noise at the first node of the receiver as a function of the determined gain, the determined intrinsic noise, and the determined composite noise.

2. The method of claim 1, further comprising:

deactivating a plurality of transmitters of a second plurality of transceivers associated with another endpoint connected to the multi-channel communication architecture,

wherein measuring the first and second values at the second node occurs during deactivation of the plurality of transmitters of the first plurality of transceivers and during deactivation of the plurality of transmitters of the second plurality of transceivers.

3. The method of claim 2,

one of the deactivated plurality of transmitters of the second plurality of transceivers comprises a partner transmitter of the receiver.

4. The method of claim 3, further comprising:

activating the deactivated plurality of transmitters of the second plurality of transceivers other than the partner transmitter,

wherein measuring the third value at the second node occurs during activation of the deactivated plurality of transmitters of the second plurality of transceivers other than the partner transmitter.

5. The method according to any one of claims 1 to 4,

the first plurality of transceivers is part of a first integrated circuit;

the deactivating the plurality of transmitters of the first plurality of transceivers comprises: a global controller associated with a second integrated circuit is in communication with a local controller of the first integrated circuit.

6. The method of claim 5, wherein the first and second integrated circuits are disposed on corresponding first and second circuit cards, the multi-channel communications architecture including a backplane connecting first and second circuit cards, the first circuit card being mounted in the first circuit card connector and the second circuit card being mounted in the second circuit card connector.

7. The method according to any of claims 1 to 6, wherein the controlling the particular transceiver causes the particular transceiver to: coupling a reference source of the particular transceiver to a first node of the receiver, measuring a first value at a second node of the receiver, and determining a gain between the first node and the second node from the measured first value comprises:

coupling the reference source to an input of a signal conditioning circuit of the receiver;

the gain is determined from a digital value provided by an analog-to-digital converter of the receiver.

8. The method of claim 7, further comprising:

the gain is adjusted according to the digital value and a target range of the digital value.

9. The method of claim 8, wherein the adjusting the gain comprises: adjusting a gain generated by the signal conditioning circuit.

10. The method of claim 1, wherein the controlling the particular transceiver causes the particular transceiver to: coupling a reference source of the particular transceiver to a first node of the receiver, measuring a first value at a second node of the receiver, and determining a gain between the first node and the second node from the measured first value comprises: writing data into at least one control register of the particular transceiver.

11. The method of any of claims 1-10, wherein the determining crosstalk noise at the first node comprises: crosstalk noise at a signal input terminal of the receiver is determined.

12. An apparatus, characterized in that the apparatus comprises:

an integrated circuit comprising a reference source, a communication interface, and a plurality of transceivers, wherein the plurality of transceivers comprise a plurality of receivers and a plurality of transmitters;

the communication interface is for controlling the plurality of transceivers to perform in-situ testing to determine crosstalk noise at an analog input of a particular receiver of the plurality of receivers, wherein the communication interface is programmable to:

deactivating the plurality of transmitters;

coupling the reference source to the analog input of the particular receiver to provide a reference signal to the analog input of the particular receiver;

providing a first digital value representative of the reference signal measured by the particular receiver;

isolating the reference source from the analog input of the receiver;

providing a second digital value representing a measure of inherent noise at the analog input of the particular receiver;

activating the deactivated plurality of transmitters;

providing a third digital value representative of complex noise at the analog input of the particular receiver.

13. The apparatus of claim 12,

the integrated circuit includes a digital signal processor associated with a particular receiver;

the particular receiver comprises an analog-to-digital converter;

the digital signal processor is configured to determine a gain between the analog input of the particular receiver and an input of the analog-to-digital converter of the particular receiver based on the first digital value.

14. The apparatus of claim 13,

the integrated circuit includes a digital signal processor associated with the particular receiver;

the digital signal processor is configured to:

determining crosstalk noise at the input of the analog-to-digital converter from the second digital value and the third digital value;

determining crosstalk noise at the analog input of the particular receiver from the determined crosstalk noise at the input of the analog-to-digital converter and the determined gain.

15. The apparatus of any one of claims 12 to 14,

the communication interface includes a plurality of writable registers such that the communication interface controls the plurality of transceivers to perform the in-place test.

16. A system, characterized in that the system comprises:

a multi-channel communication architecture;

a plurality of multi-channel endpoints, wherein each endpoint of the plurality of multi-channel endpoints comprises a plurality of transceivers coupled to the fabric, each transceiver of the plurality of transceivers comprising a transmitter and a receiver;

a controller to communicate with the plurality of multi-channel endpoints to determine in-situ crosstalk noise associated with a receiver of a first transceiver of a plurality of transceivers of a particular endpoint of the plurality of multi-channel endpoints, wherein transmitters of a plurality of transceivers of another endpoint of the plurality of multi-channel endpoints are paired with the receiver of the first transceiver, the controller to communicate with the plurality of multi-channel endpoints to:

deactivating the transmitter;

causing the first transceiver to couple a reference source of the first transceiver to an input of the receiver of the first transceiver, measure a first value at an internal terminal of the receiver of the first transceiver, and determine a gain from the measured first value;

isolating the reference source of the first transceiver from the input of the receiver;

causing the receiver of the first transceiver to measure a second value at the internal terminal and determine noise floor from the measured second value;

activating the transmitter other than the transmitter paired with the receiver of the first transceiver;

causing the receiver of the first transceiver to measure an in-situ third value at the internal terminal, determine a composite noise from the measured third value, and determine a crosstalk noise from the determined intrinsic noise, the determined composite noise, and the determined gain.

17. The system of claim 16, wherein the receiver of the first transceiver comprises an analog-to-digital converter, and wherein the gain comprises a DC gain between an input terminal of the analog-to-digital converter and an output of the analog-to-digital converter.

18. The system of claim 16 or 17, wherein the reference source comprises a bandgap voltage reference circuit.

19. The system of any of claims 16-18, wherein the first transceiver comprises a Digital Signal Processor (DSP) that determines gain, noise floor, composite noise, and in-situ crosstalk noise at the input of the receiver.

20. The system of any of claims 16-19, wherein the gain comprises a DC gain of the receiver of the first transceiver.

Background

Wired transceivers are ubiquitous in a variety of applications, such as communications infrastructures, data centers, and terminal chipsets. The wired transceiver is responsible for connecting the processing core of a communication-based integrated circuit (e.g., an integrated circuit associated with a switching fabric (fabric), traffic manager, network processor, etc.) with the outside world. In general, a particular wired transceiver serializes outgoing data received from a processing core and deserializes incoming data destined for the processing core. The wired transceiver may communicate with the outside through various communication media such as copper traces on a Printed Circuit Board (PCB), multi-mode fiber (MMF), single-mode fiber (SMF), and copper cable. In general, the processing rate (e.g., symbol rate) of a transceiver may be significantly faster than the operating frequency of the processing core of the integrated circuit. Thus, the wired transceiver may perform various functions of the integrated circuit, such as functions related to channel equalization, clock and data recovery, and retiming, in addition to serializing and deserializing data.

Disclosure of Invention

Transceivers (e.g., serial/deserializer wire transceivers) communicate with each other over a defective medium, thereby subjecting the transmitted signal to impairments such as insertion loss, reflection, and crosstalk. These impairments may collectively reduce the signal-to-noise ratio (SNR) of the communication link and increase the associated Bit Error Rate (BER). Crosstalk (referred to herein as "crosstalk noise") can be energetically large and difficult to manage because crosstalk noise can be relatively random (i.e., uncorrelated with the received data on the victim channel and possibly contained in the channel frequency). Therefore, crosstalk noise may not be easily eliminated. In addition, crosstalk noise may be amplified by a linear receiving side equalizer, which may be one or both of a forward equalization (FFE) filter and a Continuous Time Linear Equalization (CTLE) filter, etc., thereby increasing the influence of crosstalk noise and reducing BER.

Therefore, it may be beneficial to determine or estimate the amount of crosstalk noise of the receivers of the wired transceivers. One way to estimate the amount of crosstalk noise for a particular wired receiver is to estimate the theoretical crosstalk noise for the receiver using simulations, etc., based on the particular design of the receiver and the expected environment of the receiver. However, due to the complexity of the real environment, this approach may be relatively inaccurate. According to example implementations described herein, a communication system performs in-place (in place) or in-situ (in-situ) crosstalk noise measurements. More specifically, according to an exemplary implementation, for a particular receiver of a particular transceiver, the communication system is configured to perform in-situ measurements of crosstalk noise at the input of the receiver. According to an exemplary implementation, a transceiver includes components that assist in measuring in-situ crosstalk noise: a reference source and amplitude detector measuring the gain of the determinable receiver; and a noise estimator. As described herein, the noise estimator may be configured to measure the intrinsic noise at an internal node of the receiver (in the case where the partner transmitter and the intruder transmitter of the receiver are deactivated), determine the composite noise of the receiver at the internal node (in the case where the partner transmitter is deactivated and the intruder transmitter is activated), and determine a crosstalk measurement at the internal node based on the measured intrinsic noise and the composite noise. Further, according to an exemplary implementation, the noise estimator may be configured to introduce (reference) the determined crosstalk noise from the internal node to an input node of the receiver using the determined gain.

According to an aspect of the invention, a method is provided. The method includes deactivating a plurality of transmitters of a first plurality of transceivers associated with an endpoint connected to the multi-channel communication architecture. A particular transceiver of the first plurality of transceivers includes a receiver. The method includes controlling the particular transceiver to cause the particular transceiver to: coupling a reference source of the particular transceiver to a first node of the receiver, measuring a first value at a second node of the receiver, and determining a gain between the first node and the second node from the measured first value. The method comprises the following steps: controlling the particular transceiver such that the particular transceiver isolates the reference source from the first node of the receiver; the particular transceiver measuring a second value at the second node; determining, by the particular transceiver, noise floor from the measured second value; the method comprises the following steps: activating the deactivated plurality of transmitters; measuring, by the particular transceiver, a third value at the second node; determining, by the particular transceiver, a composite noise from the measured third value; the particular transceiver determines crosstalk noise at the first node of the receiver as a function of the determined gain, the determined intrinsic noise, and the determined composite noise.

According to another aspect of the invention, an apparatus is provided. The apparatus includes an integrated circuit including a reference source, a communication interface, and a plurality of transceivers. The plurality of transceivers includes a plurality of receivers and a plurality of transmitters. The communication interface is to control the plurality of transceivers to perform an in-situ test to determine crosstalk noise at an analog input of a particular receiver of the plurality of receivers. The communication interface may be programmed to: deactivating the plurality of transmitters; coupling the reference source to the analog input of the particular receiver to provide a reference signal to the analog input of the particular receiver; providing a first digital value representative of the reference signal measured by the particular receiver; isolating the reference source from the analog input of the receiver; providing a second digital value representing a measure of inherent noise at the analog input of the particular receiver; activating the deactivated plurality of transmitters; providing a third digital value representative of complex noise at the analog input of the particular receiver.

According to another aspect of the invention, a system is provided. The system includes a multi-channel communication architecture, a plurality of multi-channel endpoints, and a controller. Each endpoint includes a plurality of transceivers coupled to the architecture, each transceiver including a transmitter and a receiver. The controller communicates with the plurality of endpoints to determine in-situ crosstalk noise associated with a receiver of a first transceiver of a plurality of transceivers of a particular endpoint of the plurality of endpoints. The transmitter of the other endpoint is paired with the receiver of the first transceiver. The controller is to communicate with the plurality of endpoints to: deactivating the transmitter; causing the first transceiver to couple a reference source of the first transceiver to an input of the receiver of the first transceiver; measuring a first value at an internal terminal of the receiver of the first transceiver; a gain is determined from the measured first value. The controller is configured to: isolating the reference source of the first transceiver from the input of the receiver; causing the receiver of the first transceiver to measure a second value at the internal terminal and determine noise floor from the measured second value. The controller is further configured to: activating the transmitter other than the transmitter paired with the receiver of the first transceiver; causing the receiver of the first transceiver to measure an in-situ third value at the internal terminal, determine a composite noise from the measured third value, and determine a crosstalk noise from the determined intrinsic noise, the determined composite noise, and the determined gain.

Optionally, in any of the above aspects, in another implementation, measuring the first and second values at the second node occurs during deactivation of the plurality of transmitters of the first plurality of transceivers and deactivation of a plurality of transmitters of a second plurality of transceivers associated with another endpoint connected to the multi-communication architecture.

Optionally, in any of the above aspects, in another implementation, one of the deactivated plurality of transmitters of the second plurality of transceivers comprises a partner transmitter of the receiver.

Optionally, in any of the above aspects, in another implementation, measuring the third value at the second node occurs during activation of the plurality of transmitters of the second plurality of transceivers other than the partner transmitter.

Optionally, in any of the above aspects, in another implementation, the first plurality of transceivers are part of a first integrated circuit; the deactivating the plurality of transmitters of the first plurality of transceivers comprises: a global controller associated with a second integrated circuit is in communication with a local controller of the first integrated circuit.

Optionally, in any of the above aspects, in another implementation, the first and second integrated circuits are disposed on corresponding first and second circuit cards, and the multi-channel communication architecture includes a backplane connecting the first and second circuit cards, the first circuit card being mounted in the first circuit card connector and the second circuit card being mounted in the second circuit card connector.

Optionally, in any of the above aspects, in another implementation, the controlling the particular transceiver to cause the particular transceiver to: coupling a reference source of the particular transceiver to a first node of the receiver, measuring a first value at a second node of the receiver, and determining a gain between the first node and the second node from the measured first value comprises: coupling the reference source to an input of a signal conditioning circuit of the receiver; the gain is determined from a digital value provided by an analog-to-digital converter of the receiver.

Optionally, in any of the above aspects, in another implementation, the gain is adjusted according to the digital value and a target range of the digital value.

Optionally, in any of the above aspects, in another implementation manner, the adjusting the gain includes: adjusting a gain generated by the signal conditioning circuit.

Optionally, in any of the above aspects, in another implementation, the controlling the particular transceiver to cause the particular transceiver to: coupling a reference source of the particular transceiver to a first node of the receiver, measuring a first value at a second node of the receiver, and determining a gain between the first node and the second node from the measured first value comprises: writing data into at least one control register of the particular transceiver.

Optionally, in any of the above aspects, in another implementation, the determining crosstalk noise at the first node includes: crosstalk noise at a signal input terminal of the receiver is determined.

Optionally, in any of the above aspects, the integrated circuit comprises a digital signal processor associated with a particular receiver; the particular receiver comprises an analog-to-digital converter; the digital signal processor is configured to determine a gain between the analog input of the particular receiver and an input of the analog-to-digital converter of the particular receiver based on the first digital value.

Optionally, in any of the above aspects, in another implementation, the digital signal processor is configured to: determining crosstalk noise at the input of the analog-to-digital converter from the second digital value and the third digital value; determining crosstalk noise at the analog input of the particular receiver as a function of the determined crosstalk noise at the input of the analog-to-digital converter and the determined gain.

Optionally, in any of the above aspects, the reference source comprises a bandgap voltage reference circuit.

Drawings

Fig. 1 is a schematic diagram of an exemplary implementation providing a communication system including a serial/deserializer cable transceiver having a feature to determine in-situ crosstalk noise associated with a receiver of the transceiver.

Fig. 2 is a schematic diagram of a transceiver and its relationship to a processing core of the integrated circuit of fig. 1 provided in an exemplary implementation.

Fig. 3 is a schematic diagram of a spatial layout of the integrated circuit of fig. 1 in an exemplary implementation.

Fig. 4 is a schematic diagram of a system provided by an exemplary implementation to determine in-situ crosstalk noise associated with a receiver of a wired transceiver.

Fig. 5 is a schematic diagram of the communication system of fig. 1 implemented in a system including a backplane and a circuit card provided in an exemplary implementation.

FIG. 6 is a graphical representation of impedances associated with the architecture of the system of FIG. 5 provided by an exemplary implementation.

Fig. 7 is a flow diagram of a technique to determine receiver gain provided by an exemplary implementation.

Fig. 8 is a flow diagram of a technique provided by an exemplary implementation to determine in-situ crosstalk noise at a receiver input node based on the gain determined in fig. 7.

Detailed Description

In the context of the present application, "crosstalk noise" or "crosstalk" refers to noise that is coupled from one or more communication links, referred to as "aggressor links," to another communication link, referred to as a "victim link. Here, the "victim link" corresponds to the receiver, more specifically to the communication path of the receiver. The receiver may be paired with a transmitter and the intruder communication link corresponds to other transmitters that may generate signals that cause energy (i.e., crosstalk noise) to be coupled into the victim link. "crosstalk noise" refers to any estimate or measure of crosstalk noise, and may be Root Mean Square (RMS) noise or any other measure of crosstalk noise, and so forth.

According to one exemplary implementation, a communication system may include a plurality of serial/deserializer wireline transceivers that communicate over a plurality of channels of the communication system. In this manner, according to the example implementations described herein, the wired transceivers may be paired such that the paired transceivers communicate with each other over corresponding channels. Due to the presence of these multi-channel communications, crosstalk noise is likely to be generated at the input of a particular receiver.

According to example implementations described herein, a global controller of a multi-channel communication system may communicate with a transceiver of the system to measure in-situ (in-situ) crosstalk noise associated with a receiver of the system. More specifically, according to an exemplary implementation, the global controller may perform in-situ crosstalk noise measurements on a particular receiver (referred to herein as a "receiver under test") of a particular transceiver (referred to herein as a "transceiver under test"), as shown below. The global controller may first communicate with the transceivers corresponding to the partner transmitter and the intruder transmitter to disable or deactivate these transmitters. The global controller may then communicate with the transceiver under test to cause the receiver (as further described herein) to determine the gain of the receiver (e.g., the gain from the input of the receiver to the internal nodes of the receiver) and the noise floor (i.e., the noise when the partner transmitter and the intruder transmitter are not transmitting). The global controller may then communicate with the transceivers corresponding to the intruder transmitters to enable or activate these transmitters (leaving the partner transmitter still deactivated). With the communication system in this state, the global controller may now communicate with the transceiver under test to cause the receiver to determine its composite noise (i.e., total noise, with in-situ crosstalk noise and intrinsic noise as components), and then calculate the crosstalk noise introduced to the receiver input based on the determined intrinsic noise, the determined composite noise, and the determined gain.

More specifically, according to an exemplary implementation, a receiver under test may include several components that enable the receiver to measure various values and determine gain, noise floor, composite noise, and crosstalk noise based on these measured values. In particular, to process the measured values, the receiver may comprise a processing component, for example a Digital Signal Processor (DSP). The processing component operates at a relatively high clock frequency relative to a processing core of an integrated circuit that includes the transceiver. With this fast computation capability, the transceiver can perform various computations related to the receiver's in-situ crosstalk noise derivation. According to some implementations, the receiver includes an analog-to-digital converter (ADC) that provides digital output values from which the receiver determines gain, noise floor, and composite noise.

To determine the gain of the receiver, the receiver (or receiver in general) may include a reference source, e.g., a precision bandgap voltage reference circuit. The receiver couples the output of the reference source to the input of the receiver to establish a known reference value (a known voltage in the example of a bandgap voltage reference) at the input of the receiver. This enables the DSP to determine the gain from the known value of the source output and the digital output value provided by the ADC. According to an exemplary implementation, the gain of the receiver is a Direct Current (DC) gain of the receiver, which refers to the gain between the analog input terminal of the receiver and the ADC output. The calculation of the gain, in turn, allows the DSP to introduce the derived crosstalk measurement estimate back to the analog input terminal of the receiver.

In order to determine the intrinsic noise of the receiver under test, the reference source is isolated or decoupled from the input of the receiver; as described above, the intruder transmitter and the partner transmitter are disabled or deactivated. For this state of the communication system, the digital output value provided by the ADC represents the noise inherent to the receiver, i.e., the noise present when no source or transmitter is coupled to the analog input of the receiver.

To determine the composite noise of the receiver under test, the intruder transmitter is enabled or activated while the partner transmitter remains deactivated, as described above. For this state of the communication system, the digital output value provided by the ADC represents the composite noise of the receiver, i.e. the total noise measured at the ADC output, including the crosstalk noise component and the noise floor component. The DSP can then determine the in-situ crosstalk noise input by the receiver under test from the ADC output values representing the gain, noise floor and composite noise measurements.

In a similar manner, the global controller may control the communication system in order to measure in-situ crosstalk noise of other receivers of the communication system.

In a more specific example, fig. 1 depicts one exemplary implementation of a multi-channel (multi-channel) communication system 100 provided by some implementations. In general, communication system 100 includes a plurality of endpoint devices 110 (N exemplary endpoint devices are shown in fig. 1) that form corresponding endpoints connected to a multi-channel communication fabric (fabric) 180. As further described herein, the multi-channel communication architecture 180 may take various forms depending on the particular application. In this manner, the multi-channel communication fabric 180 may represent one or more wired communication media, such as copper traces on a PCB, cable wires, MMF fibers, SMF fibers, and so forth.

Regardless of the particular form of the multi-channel communication architecture 180, the multi-channel communication architecture 180 generally provides communication paths for a plurality of communication channels. In this manner, endpoint device 110 includes multiple transceivers, and in general, a transceiver of a particular endpoint device 100 may be paired with a corresponding transceiver of another endpoint device 100. In a more specific example, as shown in fig. 1, a particular endpoint device 110 (here, endpoint device 110-1) may include one or more integrated circuits 114, according to some implementations. According to an exemplary implementation, the integrated circuit 114 may be any of a plurality of network devices, such as a network switching fabric device, a network traffic management device, a network processing device, and the like.

As shown for endpoint device 110-1, a particular integrated circuit 114 may include one or more serial/deserialized wired transceivers 120 (referred to herein as "transceivers 120"). In general, the transceiver 120 performs analog-to-digital conversion (for received data) and digital-to-analog conversion (for data to be transmitted); for these purposes, the transceiver 120 includes a serial receiver 130 and a deserializer 124. Receiver 130 may include components such as reference source 134, ADC 138, and DSP 142. More details of the receiver 130 are described below. The transmitter 124 may generally include components such as a digital-to-analog converter (DAC) and a DSP.

As shown in fig. 1, according to an example implementation, the integrated circuit 114 may include a plurality of transceivers 120 and a common processing core 150, wherein the common processing core 150 communicates with a multi-channel communication architecture 180 through the transceivers 120. In general, processing core 150 may include one or more of the following data processing components: a Central Processing Unit (CPU), a CPU core, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), and the like.

Regardless of the particular form of the processing core 150, the processing core 150 may perform various processing functions of the integrated circuit 114, such as functions related to switching fabrics, traffic management, network data processing, etc., for data communications with the integrated circuit 114. According to an exemplary implementation, as the operating frequency of the digital processing components of transceiver 120 increases (relative to the processing frequency of processing core 150), the DSPs of receiver 130 and transmitter 124 may perform various functions of integrated circuit 114, such as functions related to channel equalization, clock and data recovery, retiming, serializing and deserializing input symbols/data, and the like. In addition, the DSP of the receiver 130 may perform various calculations related to in-situ crosstalk noise measurements of the receiver 130 and may control various aspects of the crosstalk measurement test, as further described herein.

According to an exemplary implementation, transceiver 120 may include a communication interface that enables transceiver 120 to be controlled by global controller 190 to enable and disable transmitter 124 of transceiver 120 and to control receiver 130 to enable receiver 130 to perform operations related to measuring in-situ crosstalk noise of the receiver when under test, including operations related to determining gain, noise floor, and composite noise of the receiver and determining crosstalk noise of the receiver input from the gain, noise floor, and composite noise.

For the exemplary implementation depicted in fig. 1, the integrated circuit 114 may include a local controller 145 that includes one or more addressable registers 147 that the global controller 190 may read and write to instruct the local controller 145 to: deactivating the transmitter 124 of the integrated circuit 114, activating the transmitter 124 of the integrated circuit 141, enabling operation of an amplitude detector (as further described herein) of a particular receiver under test 130 (as further described herein), enabling operation of a noise estimator (as further described herein) of the receiver 130, reading a value representative of in-situ crosstalk noise measured by the noise estimator, and so forth.

According to some implementations, in addition to registers 147, local controller 145 may include one or more processors 148 (one or more Central Processing Units (CPUs), one or more CPU processing cores, etc.). In general, the processor 148 may execute instructions 150 stored in the memory 149 of the local controller 145 to perform one or more aspects of controlling the transceiver 120 in the integrated circuit 114 to perform in-situ crosstalk noise measurements for a particular receiver 130 (of a particular transceiver 120). In general, the memory 149 is a non-transitory memory that may be comprised of semiconductor memory devices, magnetic memory devices, memristor-based devices, non-volatile memory devices, phase change memory devices, volatile memory devices, combinations of memory devices associated with any combination of the above-described memory technologies, and the like. According to further exemplary implementations, the local controller 145 may be comprised, in whole or in part, of a controller that does not execute machine-executable instructions, such as a Field Programmable Gate Array (FPGA), an Application Specific Integrated Circuit (ASIC), and so forth.

According to further exemplary implementations, each transceiver 120 of the integrated circuit 114 may include a local controller 145. For example, the local controller, amplitude detector, and noise estimator may be at least partially comprised by the DSP 142 of the receiver 130. According to further more example implementations, the integrated circuit 114 may not include a local controller in communication with the global controller 190; where appropriate, integrated circuit 114 may include a set of readable and writable registers that allow selection of the receiver under test, enabling the above-described crosstalk measurement phases of the receiver under test (i.e., phases that determine gain, noise floor, composite noise, and crosstalk noise) via register writing, and providing data representing the derived in-situ crosstalk noise for the receiver under test. Thus, depending on the particular implementation, the integrated circuit may include or not include one or more local controllers.

As shown in fig. 1, according to some implementations, global controller 190 may communicate with a communication interface of transceiver 120 through multi-channel communication fabric 180, may be separate from integrated circuit 114, and may be separate from endpoint device 110. According to further exemplary implementations, the global controller 190 may be a component of one of the integrated circuits 114. Thus, depending on the particular implementation, global controller 190 may be provided on integrated circuit 114, may be part of a particular endpoint device 110, or may be separate from endpoint device 110.

According to some implementations, global controller 190 may include one or more processors 192 (one or more Central Processing Units (CPUs), one or more processing cores, etc.) that execute machine-executable instructions 196 stored in memory 194. In addition to instructions 196, memory 194 may also store data 190 representing variables associated with in-situ crosstalk measurements and the like. Generally, memory 194 is a non-transitory memory, similar to memory 149 described above, and may be comprised of one or more memory devices.

According to further exemplary implementations, global controller 190 may be comprised, in whole or in part, of hardware that does not execute machine-executable instructions, such as an ASIC, Field Programmable Gate Array (FPGA), or the like. Accordingly, many implementations are contemplated as being within the scope of the following claims.

Referring to fig. 2, according to an exemplary implementation, in addition to the receiver 130 and the transmitter 124, the transceiver 120 may also include a clock subsystem 260 that provides clock signals to the receiver 130 and the transmitter 124. Transceiver 120 receives a signal representing serial data at an input terminal or node 216 of receiver 130, and transceiver 120 provides parallel data to processing core 150 via digital bit signal 250. Transceiver 120 receives parallel data from processing core 150 via digital bit signal 270.

As shown in fig. 2, DSP 142 of receiver 103 may be part of receive digital subsystem 240 of receiver 130. In this manner, receiving digital subsystem 240 may perform one or both of traffic management and traffic processing functions of processing core 150, and digital subsystem 240 may perform calculations to derive crosstalk noise for input node 216, as further described herein. In general, the ADC 138 of the receiver 130 is a slicer or deserializer that provides a digital output signal 230 representing digital values of a sampled analog signal provided by a sample and hold circuit (not shown). In this manner, the sample and hold circuit samples the analog output signal provided by the signal conditioning circuit 214 and provides a sampled analog signal to the input of the ADC 138. The signal conditioning circuit 214 receives the analog signal from the input node 216 and provides a conditioned signal to the analog input 220 of the ADC 138.

According to an exemplary implementation, the signal conditioning circuit 214 may include a Continuous Time Linear Equalization (CTLE) filter and may include an Automatic Gain Control (AGC) amplifier. According to one exemplary implementation, the signal conditioning circuit 214 has a relatively flat gain from near zero frequency to the channel frequency of the receiver. In other words, according to one exemplary implementation, the DC gain of the signal conditioning circuit 214 may be considered the gain of the circuit 214. In a more specific example, the signal conditioning circuit 214 may have a frequency response similar to or the same as a butterworth filter, according to some implementations. According to further exemplary implementations, the signal conditioning circuit 214 may not have a relatively flat frequency response from DC to the channel frequency and thus may have a frequency response different from the butterworth filter frequency response.

Transmitter 124 may include a serializer 266, e.g., a DAC and transmit digital subsystem 268; the transmitter 124 may include a transmit amplifier 264 that drives an analog signal to the node 216 (i.e., the node 216 may serve as an input node and an output node, according to an exemplary implementation).

Fig. 3 illustrates a spatial layout of an integrated circuit 114 provided by some implementations. The integrated circuit 114 may include a relatively large number of transceivers 120, for example, 100 to 200 transceivers 120 on a single die (single die). The processing core 150 is disposed within a central region 301 of the chip and the transceiver 120 may be disposed within an outer or peripheral region 303 of the chip surrounding the central region 301. The relatively high spatial density of the transceivers 120 is likely to result in relatively large crosstalk noise, thus increasing the importance of built-in or in-situ crosstalk noise measurement testing, as described herein.

FIG. 4 illustrates an environment 400 for in-situ crosstalk measurement testing provided by exemplary implementations. As shown in fig. 4, the decision circuit 440 of the receiver 130 includes the ADC 138 and the DSP 142. For the present exemplary implementation, DSP 142 may include components such as local controller 145, an amplitude detector 454 (as described further below in conjunction with fig. 7) to determine the gain of receiver 130, and a noise estimator 460 (as described further below in conjunction with fig. 8) to determine the noise floor, composite noise, and crosstalk noise of receiver 130. According to an exemplary implementation, these components may be formed by one or more processors 480 (one or more CPU cores, CPUs, etc.) of DSP 142, DSP 142 executing machine executable instructions 492 (i.e., software or firmware) stored in memory 494 of DSP 142. In general, memory 494 is a non-transitory memory similar to the other memories described herein and may be comprised of one or more memory devices associated with one or more memory technologies. Further, the memory 494 may store the following: data 493 relating to variables used by local controller 145, amplitude detector 454, and noise estimator 460, data representing derived in-situ crosstalk measurements, data representing digital values present at the output of ADC 138 during different phases of the crosstalk measurement test, data representing inherent noise determined by receiver 130, data representing complex noise determined by receiver 130, data representing gain determined by receiver 130, data representing intermediate values calculated as part of the crosstalk measurement test, and so forth. The global controller 190 may communicate with the local controller 145 via a communication path 403 (e.g., a path established through the fabric 180).

As shown in fig. 4, according to an exemplary implementation, the receiver 130 may include a switch 419 that may be controlled to close (close) the switch 419 to couple the bandgap voltage reference circuit 418 (i.e., the reference source 134 for the present implementation) to the input node 216 of the receiver 130. The switch 419 may also be controlled to open (open) the switch 419 to decouple or isolate the bandgap voltage reference circuit 418 from the input node 216. It should be noted that switch 419 represents the functional coupling/decoupling of bandgap voltage reference circuit 418 to input node 216, and may or may not be a device disposed between the output of circuit 418 and input node 216. For example, according to some implementations, the output terminal of the bandgap reference circuit 418 may be connected to the input node 216, and the switch 419 may be formed by a complementary metal-oxide-semiconductor (CMOS) transistor or the like disposed in the main current path of the bandgap voltage reference circuit 418 to enable and disable the circuit 418 by turning on and off, respectively. According to further exemplary implementations, the bandgap voltage reference circuit 418 may remain operational and a switch 419 may be disposed between the output terminal of the bandgap voltage reference circuit 418 and the input node 216 to selectively couple the output terminal to the node 216.

According to an exemplary implementation, the coupling of the bandgap reference source 418 to the input terminal 416 causes the input terminal 216 to increase the bandgap reference voltage (provided by the circuit 418), as shown by the summation 420. When all other transmitters 124 are deactivated, the receiver under test 130 receives as its input the voltage provided by the bandgap voltage reference circuit 418.

According to further exemplary implementations, the reference source 134 may be a source other than a bandgap voltage reference circuit.

Figure 4 depicts the coupling of the intruder transmitter and partner transmitter to the input node 216 of the receiver provided by the exemplary implementation. In particular, FIG. 4 shows partner transmitter 124-0 of receiver 130. The partner transmitter 124-0 has an associated transmitter output impedance 404 and an associated impedance 408 between the output terminal of the transmitter 124-0 and the summing node 412. In general, the summing node 412 represents the coupling of the energy generated by the intruder communication link to the input node 126 of the receiver 130. In this manner, FIG. 4 shows P exemplary intruder transmitters 124-1 through 124-P, and these intruder transmitters 124-1 through 124-P may be coupled to corresponding partner links.

In operation, energy generated by the intruder transmitters 124-1 to 124-P is coupled to the summing node 412 and is transferred to the input terminal 216 of the receiver under test through the impedance 414. For example, impedance 408 may represent an impedance of multi-channel communication architecture 180 (fig. 1), e.g., an impedance represented by copper traces of a backplane, while impedance 414 may represent an impedance locally relative to integrated circuit 114, e.g., an impedance representing connector slots and traces on a network card on which integrated circuit 114 is disposed, etc. As shown in FIG. 4, the intruder transmitters 124-1 to 124-P each have a corresponding impedance 408.

Fig. 5 is an exemplary implementation 500 of communication system 100 (fig. 1) in the presence of three endpoint devices 110 (i.e., N-3). In this regard, for the present exemplary implementation, the endpoint device 110 is a circuit card 510 that is inserted or installed in a corresponding slot connector 514. The slot connectors 514, in turn, may be part of a chassis or rack and are coupled together by copper traces of a corresponding backplane 518. For the present example, the receiver under test 130 is part of a circuit card 510-1, and the circuit card 510-1 may include one or more intruder transmitters 124. Further, for this exemplary implementation, other circuit cards 510-2 and 510-3 may include one or more transmitters 124, where one of these transmitters 124 is a partner transmitter of receiver 130 and the other transmitters 124 are intruder transmitters. As shown in fig. 5, for this exemplary implementation, circuit card 510-3 includes global controller 190.

Fig. 6 illustrates an exemplary structure 600 comprising the circuit card 510 and illustrates the corresponding impedance and crosstalk coupling of the structure 600. The intruder transmitters on circuit card 510, except for circuit card 510-1, which includes the receiver under test, provide energy (as indicated by arrows 609 and summation 612) to the crosstalk noise, respectively, and this energy propagates across backplane 518 and is affected by backplane impedance 636. The aggressor transmitters on the circuit card 510-1, including the receiver under test, also contribute energy (as shown by the arrow and sum 644) to the crosstalk noise, and the composite energy from all these aggressor transmitters propagates through the communication path 620 of the circuit card 510-1, as shown by impedance 650, and cumulatively contributes to the crosstalk noise at the input node 216, as shown by sum 660. In the in situ crosstalk noise measurement, decision circuit 440 initially determines the crosstalk noise at output 220 of signal conditioning circuit 214 of receiver 130, and then using the determined gain of circuit 214, decision circuit 440 determines the crosstalk noise at input node 216.

Fig. 7 and 8 depict exemplary techniques provided by exemplary implementations that may be performed to perform in-situ crosstalk noise measurement testing of the receiver 130. In particular, fig. 7 depicts a technique 700 that may be performed for conducting a first portion of a test to determine the internal gain of a receiver under test between its analog input terminal 216 and its ADC 138. It should be noted that technique 700 may be performed in a number of different ways depending on whether the transceiver under test includes a local controller, as described above.

Regardless of the particular architecture of the transceiver, referring to fig. 7 in conjunction with fig. 4, in accordance with the technique 700, the global controller 190 first disables or deactivates (step 704) the partner link transmitter and the intruder transmitter of the communication system; then, according to step 708, the global controller 190 enables the reference source and sets the output of the reference source to a starting value. In this manner, according to step 708, the global controller 190 may, for example, instruct the amplitude detector 454 (either through the local controller 145 or directly) to begin the gain phase of the crosstalk noise measurement test. During this gain phase, amplitude detector 454 may close switch 419 to enable bandgap voltage reference circuit 418 such that circuit 418 provides an output voltage to input node 216. In addition, the amplitude detector 454 may set the output voltage level provided by the bandgap voltage reference circuit 418 to a particular voltage level.

More specifically, according to some implementations, the bandgap voltage circuit 418 may be an optional source that may provide a range of optional voltage values, etc., as programmed by the amplitude detector 454. For example, according to some implementations, the amplitude detector 454 may initially set the output voltage of the bandgap reference voltage circuit 418 to the lowest selectable level to begin a possible iterative process to set the output of the bandgap reference source 418 to an appropriate level.

More specifically, as shown in fig. 7, according to some implementations, after setting the output of the bandgap voltage reference to a particular level, the amplitude detector 454 may determine (decision step 712) whether the sampled voltage is within the target region. For example, according to some implementations, the amplitude detector 454 may read the digital output value provided by the ADC 138 and determine from this value whether the output voltage of the bandgap voltage reference circuit is within a predefined voltage range. If not, the global controller 190 may turn the output voltage down when greater than the maximum value of the target range or turn the output voltage up when less than the lowest voltage of the target range, as shown in step 716.

After setting the output voltage of the bandgap voltage reference circuit to an appropriate level, the amplitude detector 454 may calculate the gain of the receiver 130 (i.e., the gain of the signal conditioning circuit 224) from the voltage represented by the ADC 138 and the output voltage setting of the bandgap voltage reference circuit 418, per step 720. Subsequently, the amplitude detector 454 may deactivate the bandgap voltage reference circuit by opening the switch 419, or the like, as shown in step 724.

Fig. 8 illustrates a technique 800 that may be used in an in-situ crosstalk measurement test to determine the intrinsic and composite noise and ultimately estimate the crosstalk noise at the input node 126 of a receiver under test. More specifically, referring to fig. 8 in conjunction with fig. 4, according to some implementations, technique 800 may be performed after technique 700 (fig. 7), so that when technique 800 begins, the intruder transmitter and partner transmitter remain deactivated or disabled. As shown in fig. 8, noise estimator 460 estimates (step 804) the noise floor of receiver 130. In this manner, according to an exemplary implementation, the output value provided by the ADC 138 represents the noise floor since the intruder transmitter and the partner transmitter are disabled and the bandgap voltage reference circuit 418 is disabled. Next, according to an exemplary implementation, the global controller 190 activates (step 808) the intruder transmitter, wherein the partner transmitter remains off or deactivated. In the event that the intruder transmitter is activated or enabled, then the composite noise of the receiver 130 can be calculated according to step 812. In this manner, according to an exemplary implementation, the output of the ADC 138 provides a digital value representative of the composite noise, i.e., the sum or output (at the ADC output) of the noise floor and crosstalk noise of the receiver 130, due to the enabling of the intruder transmitter and the disabling of the partner transmitter.

According to an exemplary implementation, noise estimator 460 may estimate the noise floor by performing an RMS calculation based on the output of ADC 138 to determine the noise floor, while noise estimator 430 may accordingly determine the RMS calculation of the output of ADC 138 to determine the composite noise. Thus, according to step 816, noise estimator 460 may determine crosstalk noise at the output of signal conditioning circuit 214 based on the determined composite noise and intrinsic noise; further, the noise estimator 460 may introduce the crosstalk noise measurement back to the input node 216 using the gain determined by the amplitude detector 454, per step 820.

According to an exemplary implementation, noise estimator 460 may determine the crosstalk noise of input node 216 as follows:

where "rmstop _ noise" represents the composite noise introduced to the output of the signal conditioning circuit 214 and "rmsinnsicnnoise" represents the measured intrinsic noise introduced to the output of the signal conditioning circuit 214.

While the invention has been described with respect to a limited number of implementations, those skilled in the art, having the benefit of this disclosure, will appreciate numerous modifications and variations therefrom. It is intended that the following claims cover all such modifications and changes.