Circuit, output device, detection system and method for outputting clock jitter signal
阅读说明：本技术 输出时钟抖动信号的电路、输出装置、检测系统及方法 (Circuit, output device, detection system and method for outputting clock jitter signal ) 是由 粟涛 农姗珊 陈弟虎 于 2019-09-25 设计创作，主要内容包括：本发明公开了一种输出时钟抖动信号的电路、输出装置、检测系统及方法,其中电路包括：触发电路,用于感应输入时钟信号的上升沿信号,并在感应到上升沿信号时,输出触发信号；控制电路,包括多个输出端口,用于根据触发信号控制输出端口输出使能信号；多个波形放大电路,各所述波形放大电路分别与输出端口匹配对应,且用于结合使能信号、上升沿信号和预设周期参数生成一个脉冲波形；输出电路,用于结合所有波形放大电路输出的脉冲波形生成并输出带有时钟抖动信号的波形信号。本发明根据上升沿信号生成预设周期的脉冲波形,并由普通GPIO输出波形信号,更有利于研究分析时钟信号的实际抖动情况,可广泛应用于时钟信号的抖动分析领域。(The invention discloses a circuit, an output device, a detection system and a method for outputting clock jitter signals, wherein the circuit comprises: the trigger circuit is used for sensing a rising edge signal of an input clock signal and outputting a trigger signal when the rising edge signal is sensed; the control circuit comprises a plurality of output ports and is used for controlling the output ports to output enable signals according to the trigger signals; the waveform amplifying circuits are matched and correspond to the output ports respectively and are used for generating a pulse waveform by combining an enable signal, a rising edge signal and a preset period parameter; and the output circuit is used for generating and outputting a waveform signal with a clock jitter signal by combining all the pulse waveforms output by the waveform amplifying circuit. The invention generates the pulse waveform of the preset period according to the rising edge signal, and outputs the waveform signal by the common GPIO, thereby being more beneficial to researching and analyzing the actual jitter condition of the clock signal and being widely applied to the field of jitter analysis of the clock signal.)
1. A circuit for outputting a clock jitter signal, comprising:
the trigger circuit is used for sensing a rising edge signal of an input clock signal and outputting a trigger signal when the rising edge signal is sensed;
the control circuit comprises a plurality of output ports and is used for controlling the output ports to output enable signals according to the trigger signals;
the waveform amplifying circuits are matched and correspond to the output ports respectively and are used for generating a pulse waveform by combining an enable signal, a rising edge signal and a preset period parameter;
and the output circuit is used for generating and outputting a waveform signal with a clock jitter signal by combining all the pulse waveforms output by the waveform amplifying circuit.
2. A circuit for outputting a clock jitter signal as claimed in claim 1, wherein said trigger circuit comprises a multi-bit counter for outputting a trigger signal after counting according to a rising edge signal when the rising edge signal is sensed.
3. A circuit for outputting a clock jitter signal as claimed in claim 1, wherein said control circuit comprises a multiplexer for selecting an output port according to the trigger signal and outputting the enable signal from the selected output port.
4. The circuit for outputting a clock jitter signal of claim 1, wherein each of the waveform amplifying circuits comprises a first flip-flop, a second flip-flop, a first buffer chain, a second buffer chain, and an and circuit;
the clock terminal of the second flip-flop is used for receiving an input clock signal, the data terminal of the second flip-flop receives a logic high level, the first output terminal of the second flip-flop is connected to the first input end of the and circuit through the first buffer chain, and the second output terminal of the second flip-flop is connected to the second input end of the and circuit through the second buffer chain;
the first trigger is used for receiving an enable signal and sending a reset signal to the second trigger according to the enable signal;
the second flip-flop is used for combining a reset signal, a logic high level and a rising edge signal to control the level signals of the first output terminal and the second output terminal;
the first buffer chain is used for delaying a first level signal output by a first output terminal;
the second buffer chain is used for delaying a second level signal output by a second output terminal;
and the AND gate circuit is used for combining the first level signal and the second level signal to generate and output a pulse waveform.
5. The circuit for outputting a clock jitter signal of claim 1 wherein the output circuit is an AND gate or a multi-stage cascaded AND gate.
6. A circuit for outputting a clock jitter signal as claimed in claim 2 wherein said multiplexer comprises a zero clearing circuit.
7. A clock jitter signal output apparatus, comprising a clock jitter signal acquisition circuit and a GPIO output port, wherein the clock jitter signal output circuit is connected to the GPIO output port, and wherein the clock jitter signal acquisition circuit employs a circuit for outputting a clock jitter signal according to any one of claims 1 to 6.
8. A clock jitter signal detecting system, comprising a clock jitter signal output device and an oscilloscope, wherein the clock jitter signal output device is connected with the oscilloscope, and the clock jitter signal output device adopts a clock jitter signal output device as claimed in claim 7.
9. A method of outputting a clock jitter signal, comprising the steps of:
acquiring a rising edge signal of an input clock signal, and outputting a trigger signal according to the rising edge signal;
acquiring an enable signal according to the trigger signal, and generating a pulse waveform by combining the enable signal, the rising edge signal and a preset period parameter;
and generating and outputting a waveform signal with a clock jitter signal by combining a plurality of pulse waveforms.
10. The method according to claim 9, wherein the step of obtaining a rising edge signal of the input clock signal and outputting the trigger signal according to the rising edge signal includes:
the method comprises the steps of collecting an input clock signal, recording the sequence of a rising edge signal when the rising edge signal is detected, and outputting a trigger signal according to the sequence.
Technical Field
The present invention relates to the field of jitter analysis of clock signals, and in particular, to a circuit, an output device, a detection system, and a detection method for outputting clock jitter signals.
Background
Clock jitter is the offset from the ideal clock edge that is not accumulated over time, leading and lagging with respect to the actual clock. The jitter of the clock can be divided into random jitter and inherent jitter, wherein the sources of the random jitter are thermal noise, shotnoise and flick noise, and are related to the electron and hole characteristics of electronic devices and semiconductor devices; the sources of fixed jitter are: switching power supply noise, crosstalk, electromagnetic interference, etc., are related to the design of the circuit.
The amount of jitter in a clock signal may vary between or within die (die) due to variations in semiconductor manufacturing processes, and may vary with the temperature of the digital circuit or the voltage applied to the digital circuit, so accurately measuring jitter values is of great significance to digital circuit design.
The current circuit for measuring jitter basically calculates an average value through accumulated statistics of a time period, takes the average value as a 0 value when there is no jitter, and outputs a corresponding jitter value by a difference value with the average value. Or calculating the maximum jitter value and the minimum jitter value in a time period, and outputting a difference value after calculating the difference.
Both of the above methods require statistics for a period of time before an estimated jitter value can be output, and the amount of jitter in the clock signal may vary depending on the temperature of the digital circuit or the voltage applied to the digital circuit. The heat productivity of the chip in the operation process is accumulated, and the influence on the jitter value in the temperature accumulation process is relatively large. No matter which phase of the operation the statistical time period is in, the finally output jitter value is not real-time accurate data, or there is no definite calculation formula to obtain the corresponding accurate data. Because most of signals in the modern digital chip are high-speed signals, the signals cannot be output through the ordinary GPIO, the signals need to be output after frequency reduction, and the jitter condition of the original signals cannot be reflected after the frequency reduction.
Disclosure of Invention
In order to solve one of the above technical problems, an object of the present invention is to provide a circuit, an output device, a detection system and a method for outputting a clock jitter signal in real time.
The first technical scheme adopted by the invention is as follows:
a circuit that outputs a clock jitter signal, comprising:
the trigger circuit is used for sensing a rising edge signal of an input clock signal and outputting a trigger signal when the rising edge signal is sensed;
the control circuit comprises a plurality of output ports and is used for controlling the output ports to output enable signals according to the trigger signals;
the waveform amplifying circuits are matched and correspond to the output ports respectively and are used for generating a pulse waveform by combining an enable signal, a rising edge signal and a preset period parameter;
and the output circuit is used for generating and outputting a waveform signal with a clock jitter signal by combining all the pulse waveforms output by the waveform amplifying circuit.
Further, the trigger circuit comprises a multi-bit counter, and the multi-bit counter is used for counting according to the rising edge signal when sensing the rising edge signal and outputting a trigger signal.
Further, the control circuit includes a multiplexer for selecting an output port according to the trigger signal and outputting the enable signal from the selected output port.
Further, each waveform amplifying circuit comprises a first trigger, a second trigger, a first buffer chain, a second buffer chain and an AND gate circuit;
the clock terminal of the second flip-flop is used for receiving an input clock signal, the data terminal of the second flip-flop receives a logic high level, the first output terminal of the second flip-flop is connected to the first input end of the and circuit through the first buffer chain, and the second output terminal of the second flip-flop is connected to the second input end of the and circuit through the second buffer chain;
the first trigger is used for receiving an enable signal and sending a reset signal to the second trigger according to the enable signal;
the second flip-flop is used for combining a reset signal, a logic high level and a rising edge signal to control the level signals of the first output terminal and the second output terminal;
the first buffer chain is used for delaying a first level signal output by a first output terminal;
the second buffer chain is used for delaying a second level signal output by a second output terminal;
and the AND gate circuit is used for combining the first level signal and the second level signal to generate and output a pulse waveform.
Further, the output circuit is an AND gate or a multi-stage cascade AND gate.
Further, the multiplexer includes a clear circuit.
The second technical scheme adopted by the invention is as follows:
a clock jitter signal output device comprises a clock jitter signal acquisition circuit and a GPIO output port, wherein the clock jitter signal output circuit is connected with the GPIO output port, and the clock jitter signal acquisition circuit adopts the circuit for outputting clock jitter signals.
The third technical scheme adopted by the invention is as follows:
a clock jitter signal detection system comprises a clock jitter signal output device and an oscilloscope, wherein the clock jitter signal output device is connected with the oscilloscope, and the clock jitter signal output device adopts the clock jitter signal output device.
The fourth technical scheme adopted by the invention is as follows:
a method of outputting a clock jitter signal, comprising the steps of:
acquiring a rising edge signal of an input clock signal, and outputting a trigger signal according to the rising edge signal;
acquiring an enable signal according to the trigger signal, and generating a pulse waveform by combining the enable signal, the rising edge signal and a preset period parameter;
and generating and outputting a waveform signal with a clock jitter signal by combining a plurality of pulse waveforms.
Further, the step of acquiring a rising edge signal of the input clock signal and outputting a trigger signal according to the rising edge signal includes:
the method comprises the steps of collecting an input clock signal, recording the sequence of a rising edge signal when the rising edge signal is detected, and outputting a trigger signal according to the sequence.
The invention has the beneficial effects that: according to the invention, the pulse waveform with the preset period is generated according to the rising edge signal of the input clock signal, and the waveform signal with the clock jitter signal is generated by combining a plurality of pulse waveforms.
Drawings
FIG. 1 is a block diagram of a circuit for outputting a clock jitter signal according to the present invention;
FIG. 2 is an electrical schematic of the control circuit in an exemplary embodiment;
FIG. 3 is an electrical schematic of a waveform amplification circuit in an exemplary embodiment;
FIG. 4 is a schematic diagram of pulse waveform formation in a waveform amplification circuit;
FIG. 5 is an electrical schematic diagram of an output circuit in an exemplary embodiment;
FIG. 6 is a flow chart of steps of a method of outputting a clock jitter signal according to the present invention.
Detailed Description
As shown in fig. 1, the present embodiment provides a circuit that outputs a clock jitter signal, including:
the trigger circuit is used for sensing a rising edge signal of an input clock signal and outputting a trigger signal when the rising edge signal is sensed;
the control circuit comprises a plurality of output ports and is used for controlling the output ports to output enable signals according to the trigger signals;
the waveform amplifying circuits are matched and correspond to the output ports respectively and are used for generating a pulse waveform by combining an enable signal, a rising edge signal and a preset period parameter;
and the output circuit is used for generating and outputting a waveform signal with a clock jitter signal by combining all the pulse waveforms output by the waveform amplifying circuit.
In a digital circuit, because a clock signal with too high frequency cannot be output through a common GPIO, the clock jitter signal cannot be captured and displayed by an oscilloscope. In this embodiment, by converting the input clock signal into a pulse waveform of a preset period, the output jitter is the jitter over the whole period, i.e. the jitter between two rising edges, so the falling edge of the input clock signal is not concerned for a while. The specific working principle is as follows: when the trigger circuit senses a rising edge signal, the trigger circuit sends a trigger signal to the control circuit, and the control circuit can select a corresponding output port according to the trigger signal and send an enable signal; the enabling signals are respectively connected with the output ports in a matching and corresponding mode, when the waveform amplifying circuit receives the enabling signals, the waveform amplifying circuit records the rising edge signals and converts the rising edge signals into a pulse waveform with a preset period, and therefore the clock signals are controllably amplified, and the amplification is changed to be larger in the period. And recording and converting through a plurality of waveform amplifying circuits to obtain a plurality of pulse waveforms. And superposing and outputting the obtained pulse waveforms to obtain a waveform signal, wherein the rising edges of the waveform signal correspond to the rising edges of the input clock signal one by one, so that the waveform signal is provided with a clock jitter signal, and the actual jitter condition of the input clock signal can be obtained by analyzing the waveform signal.
The trigger circuit can be implemented by a circuit having a trigger function, such as a flip-flop, a register, and a related combination of the flip-flop and the register. The control circuit is realized by adopting a circuit structure with a plurality of output channels, and when the trigger signal is received, the enable signal is output at the corresponding output port. The waveform amplifying circuit is used for generating and outputting a pulse waveform, and can be specifically realized by a trigger, a register and a relevant combination of the trigger and the register. The output circuit is used for superposing and fusing a plurality of pulse waveforms, and can be realized by adopting a logic gate structure or a signal synthesis circuit structure, and the output circuit is not limited in the embodiment and only needs to be capable of combining and outputting a plurality of signals. In fig. 1, the
Further, as a preferred embodiment, the trigger circuit includes a multi-bit counter, and the multi-bit counter is configured to output a trigger signal after counting according to a rising edge signal when the rising edge signal is sensed.
Specifically, the trigger circuit can adopt an existing 2MA bit counter circuit, wherein M is a positive integer, such as when M is 2, the trigger circuit is a 4-bit counter circuit. The specific value of M is selected according to specific use cases.
Referring to fig. 2, further as a preferred embodiment, the control circuit includes a multiplexer for selecting an output port according to the trigger signal and outputting the enable signal from the selected output port.
In particular, the
Referring to fig. 3, further as a preferred embodiment, each of the waveform amplifying circuits includes a first flip-flop, a second flip-flop, a first buffer chain, a second buffer chain, and an and circuit;
the clock terminal of the second flip-flop is used for receiving an input clock signal, the data terminal of the second flip-flop receives a logic high level, the first output terminal of the second flip-flop is connected to the first input end of the and circuit through the first buffer chain, and the second output terminal of the second flip-flop is connected to the second input end of the and circuit through the second buffer chain;
the first trigger is used for receiving an enable signal and sending a reset signal to the second trigger according to the enable signal;
the second flip-flop is used for combining a reset signal, a logic high level and a rising edge signal to control the level signals of the first output terminal and the second output terminal;
the first buffer chain is used for delaying a first level signal output by a first output terminal;
the second buffer chain is used for delaying a second level signal output by a second output terminal;
and the AND gate circuit is used for combining the first level signal and the second level signal to generate and output a pulse waveform.
In the embodiment, the waveform amplifying circuit can be realized through the two triggers, the two buffer chains and the AND gate circuit, so that the circuit structure is simpler, the integration and the realization are easier, and the hardware cost is greatly reduced.
Referring to fig. 5, further as a preferred embodiment, the output circuit is an and gate or a multi-stage cascade and gate.
The waveform combination is realized through a simple AND gate logic structure, so that the circuit structure is simpler and easy to realize. Because the AND gate provided by the existing process plant has only four inputs at most, when the number of the amplifying circuits is more than 4, the AND gate shown in FIG. 5 cannot use only one AND gate; for example, 10 amplifier circuits are needed, and it is necessary to combine 10 inputs into 3 outputs by using 2 4-input and gates +1 2-input and gates, and then combine the three outputs into one output by using 3-input and gates, where the 2 4-input and gates +1 2-input and gates and the last 3-input and gate are called multi-stage cascade and gates.
Further in a preferred embodiment, the multiplexer includes a zero clearing circuit.
Referring to FIG. 2, En0 is used to zero out the entire circuit so that it is ready to acquire a new rising edge signal.
The generation of the pulse waveform by the waveform amplifying circuit will be explained in detail with reference to fig. 4.
Referring to fig. 4, when the first rising edge of the INPUT clock signal INPUT is sensed, the flip-flop circuit sends a trigger signal to the multiplexer, and the multiplexer selects the output enable signal from the output port En1 because the En0 of the multiplexer is used as a zero clearing circuit. The enable signal is input to the first flip-
In fig. 4, a signal INPUT represents an INPUT clock signal, a signal En1 represents an enable signal, a
In summary, the circuit for outputting a clock jitter signal of the present embodiment has at least the following advantages:
(1) the structure is simple by using the all-digital standard unit structure. No other external signal is required except for the amplified pulse waveform and the reset signal.
(2) The jitter can be amplified in real time, or the high-speed signal can be converted into the low-speed signal in real time without accumulation.
(3) The amplifying circuit part completes the amplifying function by adding a fixed value to the signal period, and can simply calculate the actual waveform and the jitter on the chip through the output waveform.
The embodiment also provides a clock jitter signal output device, which comprises a clock jitter signal acquisition circuit and a GPIO output port, wherein the clock jitter signal output circuit is connected to the GPIO output port, and the clock jitter signal acquisition circuit adopts the circuit for outputting the clock jitter signal.
In the output device in this embodiment, the clock jitter signal acquisition circuit adjusts the signal period, so that the frequency reduction of the input clock signal is realized, and further, the clock jitter signal is output from the GPIO output port, which provides a foundation for subsequent clock jitter research and analysis by using an oscilloscope or other devices.
The embodiment also provides a clock jitter signal detection system, which comprises a clock jitter signal output device and an oscilloscope, wherein the clock jitter signal output device is connected with the oscilloscope, and the clock jitter signal output device adopts the clock jitter signal output device.
As shown in fig. 6, the present embodiment further provides a method for outputting a clock jitter signal, including the following steps:
s1, acquiring a rising edge signal of the input clock signal, and outputting a trigger signal according to the rising edge signal;
s2, acquiring an enable signal according to the trigger signal, and generating a pulse waveform by combining the enable signal, the rising edge signal and a preset period parameter;
and S3, combining the plurality of pulse waveforms to generate and output a waveform signal with a clock jitter signal.
Wherein the step S1 specifically includes: the method comprises the steps of collecting an input clock signal, recording the sequence of a rising edge signal when the rising edge signal is detected, and outputting a trigger signal according to the sequence.
In a digital circuit, because a clock signal with too high frequency cannot be output through a common GPIO, the clock jitter signal cannot be captured and displayed by an oscilloscope. In this embodiment, by converting the input clock signal into a pulse waveform of a preset period, the output jitter is the jitter over the whole period, i.e. the jitter between two rising edges, so the falling edge of the input clock signal is not concerned for a while. The specific working principle is as follows: when the trigger circuit senses a rising edge signal, the trigger circuit sends a trigger signal to the control circuit, and the control circuit can select a corresponding output port according to the trigger signal and send an enable signal; the enabling signals are respectively connected with the output ports in a matching and corresponding mode, when the waveform amplifying circuit receives the enabling signals, the waveform amplifying circuit records the rising edge signals and converts the rising edge signals into a pulse waveform with a preset period, and therefore the clock signals are controllably amplified, and the amplification is changed to be larger in the period. And recording and converting through a plurality of waveform amplifying circuits to obtain a plurality of pulse waveforms. And superposing and outputting the obtained pulse waveforms to obtain a waveform signal, wherein the rising edges of the waveform signal correspond to the rising edges of the input clock signal one by one, so that the waveform signal is provided with a clock jitter signal, and the actual jitter condition of the input clock signal can be obtained by analyzing the waveform signal.
While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
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