阅读说明：本技术 一种发射电路、光模块以及通信设备 (Transmitting circuit, optical module and communication equipment ) 是由 李志伟 商忠志 史文俊 于 2020-05-29 设计创作，主要内容包括：本申请的实施例提供一种发射电路、光模块以及通信设备,能够改善整体器件的带宽性能。一种发射电路包括：驱动器和直接调制激光器DML；驱动器的正极与DML的正极连接,DML的负极连接电压端,且DML的负极通过电容连接接地端；驱动器用于根据输入信号生成驱动电流,并通过驱动器的正极输出驱动电流至DML,其中,DML将驱动电流的第一部分电流通过电容输入接地端,DML将驱动电流的第二部分电流输入电压端。(Embodiments of the present application provide a transmission circuit, an optical module, and a communication apparatus, which can improve bandwidth performance of an entire device. A transmit circuit comprising: driver and direct modulation laser DML; the positive electrode of the driver is connected with the positive electrode of the DML, the negative electrode of the DML is connected with the voltage end, and the negative electrode of the DML is connected with the grounding end through a capacitor; the driver is used for generating a driving current according to an input signal and outputting the driving current to the DML through the positive electrode of the driver, wherein the DML inputs a first part of the driving current to the ground end through the capacitor, and the DML inputs a second part of the driving current to the voltage end.)

1. A transmit circuit, comprising: driver and direct modulation laser DML, wherein:

the positive electrode of the driver is connected with the positive electrode of the DML, the negative electrode of the DML is connected with a voltage end, and the negative electrode of the DML is connected with a grounding end through a capacitor;

the driver is used for generating a driving current according to an input signal and outputting the driving current to the DML through the anode of the driver, the DML inputs a first part of the driving current to the ground terminal through the capacitor, and the DML inputs a second part of the driving current to the voltage terminal.

2. The transmit circuit of claim 1,

the positive electrode of the driver and the grounding end are respectively positioned at two sides of the driver, and the positive electrode of the driver is connected with the positive electrode of the DML through a first bonding wire.

3. The transmit circuit of claim 1,

the positive electrode of the driver and the grounding end are positioned on the same side of the driver; the transition layer extending from the positive electrode of the driver to the outside of the driver is connected with the positive electrode of the DML through a first bonding wire.

4. The transmitter circuit of claim 1, wherein the capacitor is a chip capacitor, and the chip capacitor is bonded between the negative electrode of the DML and the ground terminal.

5. The transmitter circuit of claim 1, wherein the voltage terminal is connected to an external power source.

6. The transmit circuit of claim 1, wherein the voltage terminal is a negative terminal of the driver.

7. The transmit circuit of claim 1, wherein the voltage at the voltage terminal is zero.

8. The transmit circuit of any of claims 1-7, wherein the positive terminal of the driver is coupled in series with the positive terminal of the DML through a first switch.

9. The transmit circuit of any of claims 1-7, wherein the negative terminal of the DML is coupled in series with the voltage terminal via a second switch.

10. A light module, comprising: a transmitting circuit and a receiving circuit; wherein the transmit circuit is as claimed in any one of claims 1-9.

11. A communication device comprising the optical module of claim 10 and a signal source for outputting the input signal to the optical module.

Technical Field

The application relates to the technical field of optical communication, in particular to a transmitting circuit, an optical module and communication equipment.

Background

In modern optical communication networks, a direct-modulated laser (DML) is widely used because it has a simpler structure, lower cost, and lower power consumption than an electro-absorption modulator (EAM) and a Mach-Zehnder modulator (MZM). DML emits light by current drive. The DML is also modulated by modulating the current passing through the DML, so that the output optical power of the DML changes along with the modulation signal, and the electric signal is converted into an optical signal. DML can work normally and produceTo generate a modulated optical signal, two currents need to be input: bias current I_biasAnd modulating the current I_mod。

At present, a DML driver (driver) is commonly used in a transmission circuit of an optical signal to drive a DML. In a transmitting circuit, as shown in fig. 1, a DML and a driver are connected in series; wherein the positive pole (also called anode positivepole, P) of the DML serves as the radio frequency ground, and the negative pole (also called cathode negotivepole, N) of the DML is connected to the negative (-) of the driver; the positive pole (+) of the driver is connected to the positive pole P of the DML, and the capacitor C is connected between the ground GND and the positive pole P of the DML as the rf ground. In this way, the input signal is converted via the driver into a driver current I_driverTo the operating current I of the DML_laserCarrying out modulation; i is_laserAll sinking, flowing, or sucking into the drive, and I_driverAnd I_laserAre equal.

Since the positive electrode P of the DML needs to be connected to the capacitor C, in the package structure of the circuit in fig. 1, since the positive electrode P of the DML is generally on the upper surface and the negative electrode N is on the lower surface, the positive electrode P of the DML and the capacitor C can only be connected by wire-bonding (or bonding wire, wire bonding, or wire bonding). Furthermore, wire-bonding is also required between the positive pole P of the DML and the positive pole (+) of the driver, and between the negative pole N of the DML and the negative pole (-) of the driver. While modulating the current I_modGenerally, the ac signal is an ac signal, and when the ac signal flows through the wire-bonding, parasitic inductance is introduced into the wire-bonding connection, which greatly affects the overall package bandwidth and limits the improvement of the overall device performance.

Disclosure of Invention

The embodiment of the application provides a transmitting circuit, an optical module and communication equipment, which can improve the bandwidth performance of the whole device.

In a first aspect, a transmit circuit is provided. The transmission circuit includes: driver and direct modulation laser DML; the driver and the directly modulated laser DML are connected in series, for example: the positive pole of driver and DML's positive pole are connected, and voltage end is connected to DML's negative pole, and DML's negative pole passes through the electric capacity and connects the ground terminal. Wherein the driver is for the rootThe driving current is generated according to the input signal, and the driving current is output to the DML through the positive electrode of the driver, wherein the DML inputs the first part of the driving current to the ground end through the capacitor, and the DML inputs the second part of the driving current to the voltage end. Wherein, in order to drive the DML to normally work and generate the modulated optical signal, the first partial current is the modulated current I_modThe second part current is a bias current I_bias. Thus, first of all, the transmitting circuit provided in the above-mentioned solution provides a circuit configuration in which the driver and the direct modulation laser DML are connected in series, I of the driver output_driverAll through DML, there is not shunt devices in this series circuit structure, can reduce the power consumption. Moreover, the cathode of the DML is directly connected to the ground terminal GND through the capacitor C to realize radio frequency grounding, that is, the first part of current can be introduced into the ground terminal, so that when the package structure is realized, only wire-bonding needs to be performed on the anode of the driver and the anode of the DML, thereby reducing the influence on the overall package bandwidth and improving the bandwidth performance of the overall device.

In one possible design, the positive electrode of the driver and the ground terminal are respectively located at two sides of the driver, and the positive electrode of the driver is connected with the positive electrode of the DML through a first bonding wire. The positive electrode and the grounding end of the driver are respectively positioned at two sides of the driver, the positive electrode of the driver is positioned on the upper surface of the two opposite surfaces of the driver, and the grounding end is positioned on the lower surface of the two opposite surfaces of the driver; or the positive electrode of the driver is located on the lower surface of the two opposite surfaces of the driver, and the ground terminal is located on the upper surface of the two opposite surfaces of the driver. Therefore, the cathode of the DML directly grounds the radio frequency through the capacitor, namely, the first part of current can be led into the grounding end, when the packaging structure is realized, only the anode of the driver and the anode of the DML need to be wired-bonded, the influence on the whole packaging bandwidth is reduced, and the performance of the whole device is improved.

In one possible design, the positive pole of the driver and the ground terminal are located on the same side of the driver; the transition layer extending from the positive electrode of the driver to the outside of the driver is connected to the positive electrode of the DML by a first bonding wire. Therefore, the cathode of the DML directly grounds the radio frequency through the capacitor, namely, the first part of current can be led into the grounding end, when the packaging structure is realized, only the anode of the driver and the anode of the DML need to be wired-bonded, the influence on the whole packaging bandwidth is reduced, and the performance of the whole device is improved.

In one possible design, the capacitor is a chip capacitor, and the chip capacitor is soldered between the negative electrode of the DML and the ground terminal. The capacitor can be directly welded between the negative electrode of the DML and the grounding end by using the patch capacitor, so that the use of wire-bonding for connecting the capacitor is avoided.

In one possible design, the voltage terminal is used for inputting a predetermined voltage, and the voltage terminal can be connected with an external power supply to provide the predetermined voltage. The predetermined voltage may be a positive voltage or a negative voltage or a 0 voltage. Therefore, the negative electrode of the DML is led out and provides any voltage through the voltage end, and the configuration can be more flexibly carried out. The voltage at the voltage terminal may be zero, i.e. directly connected to the ground terminal (in this case, 0 voltage is provided). When the voltage end of the voltage end provides negative voltage, the voltage difference between the power end and the voltage end of the driver can be increased, so that the problem of insufficient driving voltage of the power supply voltage of the driver can be solved. In addition, the voltage terminal may be a cathode of the driver, and the cathode of the driver is used for inputting a predetermined voltage to the cathode of the DML. Or, the voltage of the voltage terminal may be zero, and the voltage terminal may directly adopt a ground terminal.

In one possible design, the DML is generally used to convert an electrical signal into an optical signal and transmit the optical signal in a transmission medium (such as an optical fiber), and when the optical signal needs to be transmitted in a time division multiplexing manner, the optical signal of the DML needs to be controlled to be turned on or off. For example: upstream signals in Passive Optical Networks (PONs). It is necessary to control the on and off of the signal light of the DML, i.e., the driver needs to support the burst function. At this time, the positive electrode of the driver is connected in series with the positive electrode of the DML through the first switch. Thus, when the first switch is turned on, the driver will drive the current I_driverThe signal light is turned on by outputting the positive electrode of the driver to the DML. Or the negative electrode of the DML is connected with the voltage end in series through the second switch. Thus, when it is secondWhen the switch is turned on, the driver drives the current I_driverThe signal light is turned on by outputting the positive electrode of the driver to the DML.

In a second aspect, there is provided a light module comprising: a transmitting circuit and a receiving circuit; wherein the transmitting circuit is the transmitting circuit in the first aspect or any one of its possible designs.

In a third aspect, a communication device is provided, which includes the optical module provided in the second aspect, and a signal source for outputting the input signal to the optical module.

For technical effects brought by any one of the design manners of the second aspect and the third aspect, reference may be made to the technical effects brought by different design manners of the first aspect, and details are not described here.

Drawings

Fig. 1 is a schematic structural diagram of a transmitting circuit provided in the prior art;

fig. 2 is a schematic structural diagram of an optical module according to an embodiment of the present application;

fig. 3 is a schematic structural diagram of a transmitting circuit according to an embodiment of the present application;

fig. 4 is a schematic diagram of an operating current of a DML provided by an embodiment of the present application;

fig. 5 is a schematic structural diagram of a transmitting circuit according to another embodiment of the present application;

fig. 6 is a schematic structural diagram of a transmitting circuit according to another embodiment of the present application;

fig. 7 is a schematic structural diagram of a transmitting circuit according to still another embodiment of the present application;

fig. 8 is a schematic diagram of a package structure of a transmitting circuit according to an embodiment of the present application;

fig. 9 is a schematic diagram of a package structure of a transmitting circuit according to another embodiment of the present application;

fig. 10 is a schematic diagram of a package structure of a transmitting circuit according to another embodiment of the present application;

fig. 11 is a schematic diagram of a package structure of a transmitting circuit according to still another embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments.

The embodiment of the application is applied to the optical module, and the optical module plays a role in photoelectric conversion. Among them, the optical module is also called an optical transmission module. Referring to fig. 2, the optical module includes a transmission circuit 21 and a reception circuit 22. The transmitting circuit 21 is used for converting the electrical signal into an optical signal and inputting the optical signal into the optical fiber 23 for transmission. The receiving circuit 22 is used for receiving the optical signal transmitted from the optical fiber 23 and converting the optical signal into an electrical signal. The transmit circuitry 21 and receive circuitry 22 in fig. 2 may multiplex optical fibers 23. Of course, the optical signals of the transmitting circuit 21 and the receiving circuit 22 can also be transmitted in two optical fibers respectively. Generally, an optical module at a transmitting end converts an electrical signal into an optical signal, and after the optical signal is transmitted through an optical fiber, an optical module at a receiving end converts the optical signal into an electrical signal.

The optical module is mainly applied to the fields of ethernet, Fiber To The Home (FTTH), Optical Transport Network (OTN), network storage, data center, and the like. Based on the above application fields, the optical module is mainly applied to the above fields as follows: optical Line Terminal (OLT), Optical Network Unit (ONU), switch, optical fiber router, video optical transceiver, optical fiber transceiver, and optical fiber network card. The communication device may further include a signal source for generating an input signal and inputting the input signal to the optical module. The optical module transmits an input signal to an optical signal through an optical fiber. Wherein the optical module supports different rate classes, for example: 1G to 10G low rate, 25G,40G,50G,100G,200G/400G, etc.

In order to realize the conversion of the electrical signal into the optical signal, an example of the present application provides a transmission circuit, as shown in fig. 3, including: driver 31 and direct modulated laser DML 32.

Wherein, the positive pole (+) of the driver 1 and the positive pole of the DML32P is connected, the negative pole N of DML32 is connected to voltage terminal Vss, and the negative pole N of DML32 is connected to ground GND via capacitor C. The driver 31 is used for generating a driving current I according to an input signal_driverAnd drives a current I through a positive pole (+) of the driver 31_driverOutput to DML 32. Wherein DML32 drives current I_driverThe first part current I1 is input to the ground GND through the capacitor C, and the DML32 drives the current I_driverThe second partial current I2 is input to the voltage terminal Vss.

In the above scheme, the input signal has an alternating current characteristic. Illustratively, the input signal may be a Radio Frequency (RF) signal. Drive current I output by driver 31_driverEqual to the operating current I flowing through the DML_laser. Wherein, the first partial current I1 is the modulation current I_modThe second partial current I2 is the bias current I_bias. In general, a DML can work normally and generate a modulated optical signal, and two currents need to be input: bias current I_biasAnd modulating the current I_mod。I_biasIs a constant number, I_biasSo that the DML operates at the normal bias point. Generally, I of DML_biasAnd about 30-60 mA. I is_modFor modulating the current, supplied by a driver, I_modUsually between 40 and 60mApp (peak to peak current, mApp for short). For a non-return-to-zero (NRZ) modulation format, the basic principle of operation of the DML is shown in fig. 4, where the DML operates at the actual operating current I_laserAt I0(I0 ═ I)_bias+I_mod/2) and I1(I1 ═ I)_bias-I_mod/2), the power of the modulated optical signal corresponding to the DML output varies from P0 to P1. Thus, the electrical signal is converted into an optical signal by the DML; the principle is substantially the same for other modulation formats, such as four-level pulse amplitude modulation (PAM 4). Wherein, fig. 3 further provides a power supply terminal Vdd of the driver 31 for providing the driver 31 with an operating voltage.

The transmitting circuit provided by the scheme provides a circuit structure with a driver and a direct modulation laser DML connected in series, and I output by the driver_driverAll through DML, the series circuit junctionAnd no shunt device is arranged in the structure, so that the power consumption can be reduced. In addition, the negative electrode N of the DML is directly connected with the ground end GND through the capacitor C to realize radio frequency grounding, namely I can be grounded_modAnd the grounding end GND is introduced, so that when the packaging structure is realized, only the positive pole (+) of the driver and the positive pole P of the DML need to be wired-bonded, the influence on the whole packaging bandwidth is reduced, and the bandwidth performance of the whole device is improved.

The voltage terminal Vss is used for inputting a predetermined voltage, and may be connected to an external power source to provide the predetermined voltage. The predetermined voltage may be a positive voltage or a negative voltage or a 0 voltage. Thus, the negative electrode N of the DML is led out and provides any voltage through the voltage end Vss, and the configuration can be more flexibly carried out. The voltage at the voltage terminal Vss may be zero, i.e. directly connected to the ground terminal GND (in this case, a 0 voltage is provided). When the voltage end Vss provides negative voltage, the voltage difference between the Vdd and the Vss can be increased, so that the problem that the driving voltage provided by the power end of the driver is insufficient can be solved. In addition, the voltage terminal Vss may be a negative electrode of the driver for inputting a predetermined voltage to a negative electrode of the DML.

DMLs are used to convert electrical signals to optical signals and transmit them over a transmission medium, such as an optical fiber. When optical signals need to be transmitted in a time division multiplexing manner, the on and off of the optical signals of the DML need to be controlled. For example: the transmission of the uplink signal of the ONU in the PON network requires that the device is in an off state when no signal is sent, and can quickly turn on or recover a normal signal, i.e., a burst mode, when the signal arrives. It is necessary to control the switching on and off of the signal light of the DML, i.e., the driver needs to support the burst function. Accordingly, embodiments of the present application provide a transmitting circuit as shown in fig. 5, the positive pole (+) of the driver 31 is connected in series with the positive pole P of the DML32 through the first switch K1. Thus, when the first switch K1 is turned on, the driver 31 will drive the current I_driverThe signal light is turned on by outputting its positive electrode to the DML 32. Alternatively, a transmission circuit is provided, as shown in fig. 6, the negative electrode N of the DML32 is connected in series to the voltage terminal Vss through the second switch K2. Thus, when the second switch K2 is turned on, the driver 31 will drive the current I_driverOutput to D through its positive pole (+)And ML32, realizing the switching on of the signal light. When the optical signal transmission is not required, the first switch K1 (or the second switch K2) is controlled to be turned off.

Fig. 5 and 6 above provide a placement position of the burst switch (the first switch K1 or the second switch K2) for controlling the burst function of the driver 31, respectively. Therefore, the burst switch is controlled to be switched between an on state and an off state by an external input Burst Enable (BEN) signal, and the interruption and the opening of the optical signal output by the DML are further controlled. Illustratively, the burst switch may be implemented using a Field Effect Transistor (FET), a Heterojunction Bipolar Transistor (HBT), a High Electron Mobility Transistor (HEMT), or a Bipolar Junction Transistor (BJT), etc.

In one example, the driver 31 includes at least one transistor connected to form a single-ended driver circuit. As shown in fig. 7, the driver 31 may employ a transistor including an emitter (emitter, e), a base (base, b), and a collector (collector, c). Wherein the base b inputs the input signal, and the emitter e is connected to the anode P of the DML32 as the anode (+) of the driver 31; the collector c serves as a power supply terminal Vdd of the driver 31. The transistor can be realized by FET, HBT, HEMT or BJT.

Referring to fig. 8, in conjunction with the transmitting circuit provided in fig. 3, a package structure of the transmitting circuit is provided. Wherein, the positive pole (+) of the driver 81 and the ground terminal GND are respectively located at two sides of the driver 81, and the positive pole (+) of the driver 81 is connected with the positive pole P of the DML82 through the first bonding wire L1; the negative pole N of DML82 is connected to voltage terminal Vss.

Wherein, the positive pole (+) of the driver 81 and the ground terminal GND are respectively located at both sides of the driver 81, meaning that the positive pole (+) of the driver 81 is located at the upper surface of the two opposite surfaces of the driver 81, and the ground terminal GND is located at the lower surface of the two opposite surfaces of the driver 81; or the positive pole (+) of the driver 81 is located at the lower surface of the opposite two surfaces of the driver 81, and the ground terminal GND is located at the upper surface of the opposite two surfaces of the driver 81. In addition, fig. 8 also shows the electrodes for inputting signals such as input signals, Vdd, etc. on the same side of the driver as the positive pole (+). Thus, since the cathode N of the DML directly connects the radio frequency to the ground through the capacitor C, i.e. I can be connected_modWhen the package structure is implemented, wire-bonding is only needed to be performed on the positive pole (+) of the driver 31 and the positive pole P of the DML, so that the influence on the overall package bandwidth is reduced, and the bandwidth performance of the overall device is improved.

In addition, the capacitor C may be a chip capacitor, and the chip capacitor C is soldered between the negative electrode N of the DML82 and the ground GND. The capacitor C can be directly welded between the negative electrode N of the DML82 and the ground end GND by using the patch capacitor, so that the capacitor C is prevented from being connected by wire-bonding.

Further, as shown in fig. 8, when the voltage terminal Vss is the negative pole (-) of the driver 81, the negative pole (-) of the driver 81 is located on the same side of the driver 81 as the positive pole (+) of the driver 81; the negative electrode N of the DML82 is connected to the negative electrode (-) of the driver 81 through the second bonding wire L2, and the negative electrode (-) of the driver 81 is used to input a predetermined voltage to the negative electrode N of the DML.

In connection with the transmitting circuit shown in fig. 5, in the transmitting circuit packaging structure, the first switch K1 may be included in the driver, where the first switch K1 is connected in series with the anode of the driver 81. When the first switch K1 is turned on, the driver 81 will drive the current I_driverOutput to the DML82 via the first switch K1 and the positive pole (+) of the driver 81.

In conjunction with the transmitting circuit shown in fig. 6, as shown in fig. 9, the package structure includes the second switch K2, and the second switch K2 is connected in series between the negative electrode N of the DML82 and the voltage terminal Vss. When the second switch K2 is turned on, the driver 81 will drive the current I_driverOutput to the DML82 through the positive (+) of the driver 81. The second switch K2 may be included in the driver when the voltage terminal Vss is the negative pole (-) of the driver.

Referring to fig. 10 in conjunction with the transmitting circuit provided in fig. 3, the positive pole (+) of the driver 91 and the ground terminal GND are located on the same side of the driver 91; the transition layer 93, in which the positive pole (+) of the driver 91 is extended to the outside of the driver 91, is connected to the positive pole P of the DML92 by a first bonding wire L1. Thus, due toThe negative electrode N of the DML directly grounds the radio frequency through the capacitor C, i.e. I can be grounded_modWhen the package structure is realized, wire-bonding is only needed to be performed on the positive pole (+) of the driver and the positive pole P of the DML, so that the influence on the overall package bandwidth is reduced, and the bandwidth performance of the overall device is improved.

And a patch capacitor C is pasted and welded between the negative electrode N of the DML92 and the ground end GND. This approach may avoid the use of wire-bonding connecting capacitors C.

As shown in fig. 10, when the voltage terminal Vss is the negative pole (-) of the driver 91, the negative pole (-) of the driver 91 is located on the same side of the driver 91 as the positive pole (+) of the driver 91; the cathode N of the DML92 and the cathode (-) of the driver 91 are made of the same material, and the cathode (-) of the driver 91 is used for inputting a predetermined voltage to the cathode of the DML.

When the transmitting circuit shown in conjunction with fig. 5 includes the first switch K1, the first switch K1 may be included in the driver in a package structure, and the first switch K1 is connected in series with the anode of the driver 91; when the first switch K1 is turned on, the driver 91 will drive the current I_driverThe voltage is outputted to the DML92 via the first switch K1 and the positive pole (+) of the driver 91.

When the transmitting circuit shown in conjunction with fig. 6 includes the second switch K2, as shown in fig. 11, in the package structure, the second switch K2 is connected in series between the negative electrode N of the DML92 and the voltage terminal Vss; when the second switch K2 is turned on, the driver 91 will drive the current I_driverOutput to DML92 through the positive (+) of driver 91. The second switch K2 may be included in the driver when the voltage terminal Vss is the negative electrode of the driver.

Although the present application has been described in conjunction with specific features and embodiments thereof, it will be evident that various modifications and combinations can be made thereto without departing from the spirit and scope of the application. Accordingly, the specification and figures are merely exemplary of the present application as defined in the appended claims and are intended to cover any and all modifications, variations, combinations, or equivalents within the scope of the present application. It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.