阅读说明：本技术 用于可见光通信的bc类氮化镓mos管推挽式发射驱动器 (Push-pull emission driver of BC-class gallium nitride MOS (metal oxide semiconductor) tube for visible light communication ) 是由 王秀宇 唐伎伶 李�亨 毛旭瑞 于 2019-08-08 设计创作，主要内容包括：一种用于可见光通信的BC类氮化镓晶体管推挽式发射驱动器,用于可见光通信系统的发射部分,包括有：信号处理电路,用于将接收到的输入信号转换成两路差分信号,再进行放大处理后输出；LED光发射机推挽驱动电路,LED光发射机推挽驱动电路与信号处理电路的输出端相连,通过两个电压输入端具有压差的推挽电路接收信号处理电路的两路差分信号,去驱动和调制位于源端的发光二极管LED通过明和暗的转换实现信号驱动,并通过透镜聚焦输出。本发明B-C类功率放大的推挽结构,提升了发射机开关速度和效率,使发射机的驱动管处于高效率、高速率,信号功率放大处于B-C类功率放大,使导通角减小,减少了和载流子抽取重叠时间,提高了整个系统效率。(A class BC gallium nitride transistor push-pull emission driver for visible light communications, for use in an emission portion of a visible light communications system, comprising: the signal processing circuit is used for converting the received input signals into two paths of differential signals, and then outputting the differential signals after amplification processing; the LED light emitter push-pull driving circuit is connected with the output end of the signal processing circuit, receives two paths of differential signals of the signal processing circuit through the push-pull circuit with the voltage difference at the two voltage input ends, drives and modulates the light emitting diode LED at the source end to realize signal driving through light and dark conversion, and focuses and outputs the signals through the lens. The push-pull structure of B-C type power amplification of the invention improves the switching speed and efficiency of the transmitter, enables the driving tube of the transmitter to be in high efficiency and high speed, enables the signal power amplification to be in B-C type power amplification, reduces the conduction angle, reduces the time of overlapping with the extraction of carriers, and improves the efficiency of the whole system.)

1. A class BC gallium nitride transistor push-pull emissive driver for visible light communications, for use in an emissive portion of a visible light communications system, comprising:

the signal processing circuit (1) is used for converting the received input signal (a) into two paths of differential signals, and then outputting the signals after amplification processing;

The LED light emitter push-pull driving circuit (2) is connected with the output end of the signal processing circuit (1), two paths of differential signals of the signal processing circuit (1) are received through a push-pull circuit with voltage difference at two voltage input ends, a light emitting diode LED at a source end is driven and modulated to realize signal driving through light and dark conversion, and the signal is focused and output through the lens (3).

2. the BC class-BC gallium-nitride-transistor push-pull emission driver for visible light communication according to claim 1, wherein the signal processing circuit (1) comprises: the LED driving circuit comprises a balun differential signal conversion circuit (11) for converting an input signal (a) into two paths of differential signals and a gallium nitride amplification driving circuit (12) connected to the output end of the balun differential signal conversion circuit (11) and used for receiving the two paths of differential signals, wherein the gallium nitride amplification driving circuit (12) is used for amplifying the two paths of differential signals respectively and outputting the amplified signals to the LED light emitter push-pull driving circuit (2).

3. The BC class-BC GaN transistor push-pull transmission driver for visible light communication according to claim 2, wherein the balun differential signal conversion circuit (11) is composed of a first balun transformer T1 and a second balun transformer T2, wherein one end of a primary winding of the first balun transformer T1 is connected to the input signal (a) through a capacitor C1, and the other end is grounded, one end of a secondary winding of the first balun transformer T1 is configured as a Control signal output Control, and is connected to the Control input terminal of the LED light emitter push-pull driving circuit (2), the other end is connected to one end of a primary winding of a second balun transformer T2 through a first DC blocking capacitor C2, the other end of the primary winding of the second balun transformer T2 is grounded, one end of a secondary winding of the second balun transformer T2 is configured as a first differential signal, and is connected to one signal input terminal of the GaN amplification driving circuit (12) through a second DC blocking capacitor C3, the other end of the secondary coil of the second balun transformer T2 forms a second path of differential signals, and is connected with the other signal input end of the gallium nitride amplification driving circuit (12) through a third blocking capacitor C4.

4. The BC class-BC GaN transistor push-pull transmission driver for visible light communication according to claim 3, wherein the GaN amplifying driver circuit (12) is composed of a first common source amplifier (121) and a second common source amplifier (122), wherein a signal input terminal of the first common source amplifier (121) is connected to an output terminal of a second DC blocking capacitor C3 for receiving a first path of differential signals, and an output terminal of the first common source amplifier (121) constitutes an amplified in-phase differential output signal Vin-p, which is connected to a driving input terminal of the LED optical transmitter push-pull driving circuit (2); and the signal input end of the second common source amplifier (122) is connected with the output end of the third blocking capacitor C4 to receive a second path of differential signal, and the signal output end of the second common source amplifier (122) forms an amplified inverted differential output signal Vin-n which is connected with the other driving input end of the LED light emitter push-pull driving circuit (2).

5. The BC class-BC GaN transistor push-pull emission driver for visible light communication according to claim 4, wherein the first common source amplifier (121) and the second common source amplifier (122) are identical in structure and each include: a first gallium nitride MOS transistor M1 or a second gallium nitride MOS transistor M2, a gate of the first gallium nitride MOS transistor M1 or the second gallium nitride MOS transistor M2 constitutes a differential signal output terminal whose input terminal is connected to the balun differential signal conversion circuit (11), the gate is further connected to a voltage VDD through a first resistor R1 or a fifth resistor R5, and is grounded through a second resistor R2 or a sixth resistor R6, a source of the first gallium nitride MOS transistor M1 or the second gallium nitride MOS transistor M2 is grounded through a fourth resistor R4 or an eighth resistor R8, a drain of the first gallium nitride MOS transistor M1 or the second gallium nitride MOS transistor M2 constitutes an amplified differential signal output terminal, and a drain of the first gallium nitride MOS transistor M1 or the second gallium nitride MOS transistor M2 is further connected to the voltage VDD through a third resistor R3 or a seventh resistor R7; the grid electrode of a first gallium nitride MOS tube M1 in the first common source amplifier (121) forms a signal input end, the first differential signal output by the balun differential signal conversion circuit (11) is connected through a second blocking capacitor C3, the drain electrode of the first gallium nitride MOS tube M1 forms an amplified in-phase differential output signal Vin-p, the grid electrode of a second gallium nitride MOS tube M2 in the second common source amplifier (122) is connected with the second differential signal output by the balun differential signal conversion circuit (11) through a third blocking capacitor C4, and the drain electrode of the second gallium nitride MOS tube M2 forms an amplified inverted differential output signal Vin-n.

6. the BC class-BC GaN transistor push-pull emission driver for visible light communication according to claim 1, wherein the LED light emitter push-pull driving circuit (2) comprises a push-pull circuit (21) composed of a third GaN MOS transistor M3 and a fourth GaN MOS transistor M4 for driving the LED, and an adjustable residual carrier extraction circuit (22) connected in parallel to the LED for limiting the speed of the emitter, wherein the gate of the third GaN MOS transistor M3 constituting the push-pull circuit (21) is connected to the in-phase differential output signal Vin-p outputted from the signal processing circuit (1), the drain of the third GaN MOS transistor M3 is connected to the first input voltage VLED1, the gate of the fourth GaN MOS transistor M4 is connected to the inverted differential output signal Vin-n outputted from the signal processing circuit (1), the drain of the fourth gallium nitride MOS transistor M4 is connected to the second input voltage VLED2, the sources of the third gallium nitride MOS transistor M3 and the fourth gallium nitride MOS transistor M4 together form a driving signal output terminal connected to the light emitting diode LED for driving and modulating the output of the light emitting diode LED, a first freewheeling diode D1 is connected between the drain and the source of the third gallium nitride MOS transistor M3, and a second freewheeling diode D2 is connected between the drain and the source of the fourth gallium nitride MOS transistor M4.

7. The push-pull emissive driver of class BC gallium nitride transistors for visible light communication of claim 6, wherein the first input voltage VLED1 is greater than the second input voltage VLED 2.

8. the class BC gallium nitride transistor push-pull emissive driver for visible light communication of claim 6, the adjustable residual carrier extraction circuit (22) is characterized by comprising a fifth gallium nitride MOS tube M5 and an AND gate XOR connected to the grid of the fifth gallium nitride MOS tube M5, the drain of the fifth gallium nitride MOS transistor M5 is connected to the input terminal of the light emitting diode LED through the tenth resistor, the source of the fifth gan MOS transistor M5 is connected to the ground terminal of the LED, the output end of the and gate XOR is connected to the gate of the fifth gallium nitride MOS transistor M5, one input end of the AND gate XOR is directly connected with the Control signal output Control of the signal processing circuit (1), the other input of the and gate XOR is connected to the Control signal output Control of the signal processing circuit (1) via an RC circuit formed by a ninth resistor R9 and a fifth capacitor C5.

9. The BC class-BC GaN transistor push-pull emission driver for visible light communication according to claim 6, wherein the static operating voltage of the first common source amplifier (121) and the second common source amplifier (122) in the signal processing circuit (1) is smaller than the turn-on voltage of the third GaN MOS transistor M3 and the fourth GaN MOS transistor M4 constituting the push-pull circuit (21) in the LED optical transmitter push-pull driving circuit (2), and the conduction angle of the LED is smaller than 90 degrees when it is turned on, i.e. in the BC class-power amplification state.

Technical Field

The invention relates to a push-pull emission driver of a gallium nitride transistor. In particular to a novel push-pull structure emission driver of a BC class power amplification gallium nitride MOS tube for visible light communication.

background

In recent years, with the spread of Light Emitting Diodes (LEDs), the development of Visible Light Communication (Visible Light Communication) technology has been rapidly progressing. Meanwhile, the LED also gradually becomes a luminous light source for illumination, and the high-power luminous LED is suitable for high-speed communication while meeting the illumination requirement of people due to the characteristics of high efficiency, long service life, low power consumption and the like, wider modulation bandwidth and low complexity. Therefore, the design of coexistence of illumination and visible light communication is increasingly used, and is receiving attention and research of researchers.

Fig. 1 shows a general block diagram of a system for visible light communication, which mainly includes an LED driver and a receiver of a transmitter, where in the transmitter of the visible light communication system, an LED driving circuit needs to be designed to transmit a signal, and a physical bandwidth, a transmission rate, and a transmission efficiency of the system need to be considered. Currently, most researchers rarely consider the power efficiency and the actual lighting power of an LED driver, and the system efficiency of an LED communication system transmitter achieving 1Mbps baud rate is 81.5%. Such efficiency and transmission rate are not practical to meet the requirements of LED driven transmitters. Therefore, LED driver transmitters in visible light communication systems require higher system efficiency, high power, and higher transmission rates.

Disclosure of Invention

The invention aims to provide a BC gallium nitride MOS tube push-pull emission driver for visible light communication, which can improve the speed and the system efficiency of an emitter.

The technical scheme adopted by the invention is as follows: a class BC gallium nitride transistor push-pull emission driver for visible light communications, for use in an emission portion of a visible light communications system, comprising:

The signal processing circuit is used for converting the received input signals into two paths of differential signals, and then outputting the differential signals after amplification processing;

The LED light emitter push-pull driving circuit is connected with the output end of the signal processing circuit, receives two paths of differential signals of the signal processing circuit through the push-pull circuit with the voltage difference at the two voltage input ends, drives and modulates the light emitting diode LED at the source end to realize signal driving through light and dark conversion, and focuses and outputs the signals through the lens.

The signal processing circuit comprises: the LED driving circuit comprises a balun differential signal conversion circuit for converting an input signal into two paths of differential signals and a gallium nitride amplification driving circuit connected to the output end of the balun differential signal conversion circuit and used for receiving the two paths of differential signals, wherein the gallium nitride amplification driving circuit amplifies the two paths of differential signals respectively and outputs the amplified signals to the LED light emitter push-pull driving circuit.

The balun differential signal conversion circuit is composed of a first balun transformer T1 and a second balun transformer T2, wherein, one end of the primary coil of the first balun transformer T1 is connected with the input signal through a capacitor C1, and the other end is grounded, one end of the secondary coil of the first balun transformer T1 forms a Control signal output Control which is connected with a Control input end of the LED light emitter push-pull driving circuit, the other end of the secondary coil is connected with one end of the primary coil of a second balun transformer T2 through a first blocking capacitor C2, the other end of the primary coil of the second balun transformer T2 is grounded, one end of the secondary coil of the second balun transformer T2 forms a first path of differential signal, the other end of the secondary coil of the second balun transformer T2 forms a second path of differential signals, and the other signal input end of the gallium nitride amplification driving circuit is connected through a third DC blocking capacitor C4.

The gallium nitride amplification driving circuit is composed of a first common source amplifier and a second common source amplifier, wherein the signal input end of the first common source amplifier is connected with the output end of a second blocking capacitor C3 to receive a first path of differential signals, the output end of the first common source amplifier forms an amplified in-phase differential output signal Vin-p, and is connected with one driving input end of the LED light emitter push-pull driving circuit; and the signal input end of the second common source amplifier is connected with the output end of the third blocking capacitor C4 to receive a second path of differential signal, and the signal output end of the second common source amplifier forms an amplified inverted differential output signal Vin-n which is connected with the other driving input end of the LED light emitter push-pull driving circuit.

The first common source amplifier and the second common source amplifier have the same structure and both comprise: a first gallium nitride MOS transistor M1 or a second gallium nitride MOS transistor M2, a gate of the first gallium nitride MOS transistor M1 or the second gallium nitride MOS transistor M2 constitutes an input end connected to a differential signal output end of the balun differential signal conversion circuit, the gate is further connected to a voltage VDD through a first resistor R1 or a fifth resistor R5, and is grounded through a second resistor R2 or a sixth resistor R6, a source of the first gallium nitride MOS transistor M1 or the second gallium nitride MOS transistor M2 is grounded through a fourth resistor R4 or an eighth resistor R8, a drain of the first gallium nitride MOS transistor M1 or the second gallium nitride MOS transistor M2 constitutes an amplified differential signal output end, and a drain of the first gallium nitride MOS transistor M1 or the second gallium nitride MOS transistor M2 is further connected to the voltage VDD through a third resistor R3 or a seventh resistor R7; the grid electrode of the first gallium nitride MOS tube M1 in the first common source amplifier forms a signal input end, the first path of differential signal output by the balun differential signal conversion circuit is connected through a second blocking capacitor C3, the drain electrode of the first gallium nitride MOS tube M1 in the first common source amplifier forms an amplified in-phase differential output signal Vin-p, the grid electrode of the second gallium nitride MOS tube M2 in the second common source amplifier is connected with the second path of differential signal output by the balun differential signal conversion circuit through a third blocking capacitor C4, and the drain electrode of the second gallium nitride MOS tube M2 in the second common source amplifier forms an amplified inverted differential output signal Vin-n.

The push-pull driving circuit of the LED light emitter comprises a push-pull circuit which is composed of a third gallium nitride MOS tube M3 and a fourth gallium nitride MOS tube M4 and is used for driving a light emitting diode LED, and an adjustable residual carrier extraction circuit which is connected in parallel to the light emitting diode LED and enables the speed of the emitter not to be limited, wherein the grid electrode of the third gallium nitride MOS tube M3 which forms the push-pull circuit is connected with an in-phase differential output signal Vin-p output by a signal processing circuit, the drain electrode of the third gallium nitride MOS tube M3 is connected with a first input voltage VLED1, the grid electrode of the fourth gallium nitride MOS tube M4 is connected with an anti-phase differential output signal Vin-n output by the signal processing circuit, the drain electrode of the fourth gallium nitride MOS tube M4 is connected with a second input voltage VLED2, the source electrodes of the third gallium nitride MOS tube M3 and the fourth gallium nitride MOS tube M4 jointly form a driving signal output end which is connected with the light emitting diode LED, the output of the light emitting diode LED is driven and modulated, a first freewheeling diode D1 is connected between the drain electrode and the source electrode of the third gallium nitride MOS tube M3, and a second freewheeling diode D2 is connected between the drain electrode and the source electrode of the fourth gallium nitride MOS tube M4.

the first input voltage VLED1 is greater than the second input voltage VLED 2.

The adjustable residual carrier extraction circuit comprises a fifth gallium nitride MOS tube M5 and an AND gate XOR connected to the gate of the fifth gallium nitride MOS tube M5, the drain of the fifth gallium nitride MOS tube M5 is connected to the input end of the light emitting diode LED through a tenth resistor, the source of the fifth gallium nitride MOS tube M5 is connected to the ground end of the light emitting diode LED, the output end of the AND gate XOR is connected to the gate of the fifth gallium nitride MOS tube M5, one input end of the AND gate XOR is directly connected to the Control signal output Control of the signal processing circuit, and the other input end of the AND gate XOR is connected to the Control signal output Control of the signal processing circuit through an RC circuit composed of a ninth resistor R9 and a fifth capacitor C5.

the static working voltage of the first common source amplifier and the second common source amplifier in the signal processing circuit is smaller than the starting voltage of a third gallium nitride MOS tube M3 and a fourth gallium nitride MOS tube M4 which form a push-pull circuit in the push-pull driving circuit of the LED light emitter, and the conduction angle of the LED is smaller than 90 degrees when the LED is conducted, namely, the LED is in a BC type power amplification state.

The BC gallium nitride MOS tube push-pull type emission driver for visible light communication has the advantages that the B-C type power amplification push-pull structure enables the driving tube of the emitter to be in high efficiency and high speed, and the BC gallium nitride MOS tube push-pull type emission driver has great application value. Has the following advantages:

1. The invention adopts the novel gallium nitride field effect transistor with the advantages of smaller on-resistance, lower switching loss and the like as the LED driving tube, thereby improving the switching speed and efficiency.

2. A novel push-pull structure is adopted to drive the LED, so that the service efficiency of a transmitter for driving the high-power LED is improved, and the driving speed is not reduced; the LED is in bright-dark conversion to improve the speed, and meanwhile, the driving power device is in a switch state to improve the efficiency of the whole system of the transmitter. And the extraction circuit of the residual carriers of the junction capacitance of the LED is designed, so that the speed of the transmitter is not limited.

3. The signal power amplification is in B-C power amplification, so that the conduction angle is reduced, the overlapping time with the carrier extraction is reduced, and the efficiency of the whole system is improved.

In conclusion, the novel B-C type power amplification push-pull structure driving circuit transmitter provided by the invention has a good application prospect.

Drawings

FIG. 1 is a general block diagram of a prior art system for visible light communication;

FIG. 2 is a block diagram of a class BC GaN MOS transistor push-pull emission driver for visible light communication according to the present invention;

FIG. 3 is a circuit schematic of the signal processing circuit of the present invention;

FIG. 4 is a schematic circuit diagram of an LED driver circuit of the present invention;

FIG. 5 is a schematic diagram of class B power-amplified conduction angles;

FIG. 6 is a schematic diagram of B-C power amplification conduction angles in the present invention.

Detailed Description

the push-pull emission driver of a class BC gallium nitride MOS transistor for visible light communication according to the present invention is described in detail below with reference to the embodiments and the accompanying drawings.

The BC-class gallium nitride MOS tube push-pull type emission driver for visible light communication adopts the gallium nitride field effect transistor as a driving tube, and designs a novel B-C-class power amplification push-pull structure to ensure that the driving tube of the emitter is in high efficiency and high speed, thereby having great application value.

As shown in fig. 2, the BC-class gallium nitride MOS transistor push-pull emission driver for visible light communication according to the present invention is used for an emission portion of a visible light communication system, and includes:

The signal processing circuit 1 is used for converting the received input signal a into two paths of differential signals, and then outputting the differential signals after amplification processing; the LED light emitter push-pull driving circuit 2 is connected with the output end of the signal processing circuit 1, two paths of differential signals of the signal processing circuit 1 are received through a push-pull circuit with voltage difference at two voltage input ends, a light emitting diode LED at a source end is driven and modulated to realize signal driving through light and dark conversion, and the signal is focused and output through a lens (3).

as shown in fig. 3, the signal processing circuit 1 includes: the circuit comprises a balun differential signal conversion circuit 11 for converting an input signal a into two paths of differential signals and a gallium nitride amplification driving circuit 12 connected to the output end of the balun differential signal conversion circuit 11 and used for receiving the two paths of differential signals, wherein the gallium nitride amplification driving circuit 12 is used for amplifying the two paths of differential signals respectively and then outputting the amplified signals to the LED light emitter push-pull driving circuit 2.

The balun differential signal conversion circuit 11 is composed of a first balun transformer T1 and a second balun transformer T2, wherein, one end of the primary coil of the first balun transformer T1 is connected with the input signal a through a capacitor C1, the other end is grounded, one end of the secondary coil of the first balun transformer T1 forms a Control signal output Control, the Control signal output Control is connected with the Control input end of the LED light emitter push-pull driving circuit 2, the other end of the secondary coil is connected with one end of the primary coil of a second balun transformer T2 through a first blocking capacitor C2, the other end of the primary coil of the second balun transformer T2 is grounded, one end of the secondary coil of the second balun transformer T2 forms a first path of differential signal, one signal input end of the gallium nitride amplifying and driving circuit 12 is connected through a second blocking capacitor C3, the other end of the secondary coil of the second balun transformer T2 forms a second path of differential signals, the other signal input end of the gallium nitride amplification driving circuit 12 is connected through a third blocking capacitor C4.

The gallium nitride amplification driving circuit 12 is composed of a first common source amplifier 121 and a second common source amplifier 122, wherein a signal input end of the first common source amplifier 121 is connected to an output end of a second blocking capacitor C3 to receive a first path of differential signal, and an output end of the first common source amplifier 121 constitutes an amplified in-phase differential output signal Vin-p, which is connected to a driving input end of the LED optical transmitter push-pull driving circuit 2; the signal input end of the second common-source amplifier 122 is connected to the output end of the third dc blocking capacitor C4 to receive the second path of differential signal, and the signal output end of the second common-source amplifier 122 forms an amplified inverted differential output signal Vin-n, which is connected to the other driving input end of the LED light emitter push-pull driving circuit 2.

The first common source amplifier 121 and the second common source amplifier 122 have the same structure, and both include: a first gallium nitride MOS transistor M1 or a second gallium nitride MOS transistor M2, a gate of the first gallium nitride MOS transistor M1 or the second gallium nitride MOS transistor M2 constitutes an input end connected to a differential signal output end of the balun differential signal conversion circuit 11, the gate is further connected to a voltage VDD through a first resistor R1 or a fifth resistor R5, and is grounded through a second resistor R2 or a sixth resistor R6, a source of the first gallium nitride MOS transistor M1 or the second gallium nitride MOS transistor M2 is grounded through a fourth resistor R4 or an eighth resistor R8, a drain of the first gallium nitride MOS transistor M1 or the second gallium nitride MOS transistor M2 constitutes an amplified differential signal output end, and a drain of the first gallium nitride MOS transistor M1 or the second gallium nitride MOS transistor M2 is further connected to the voltage VDD through a third resistor R3 or a seventh resistor R7; the gate of the first gallium nitride MOS transistor M1 in the first common-source amplifier 121 forms a signal input end, the first differential signal output by the balun differential signal conversion circuit 11 is connected through the second dc blocking capacitor C3, the drain of the first gallium nitride MOS transistor M1 forms an amplified in-phase differential output signal Vin-p, the gate of the second gallium nitride MOS transistor M2 in the second common-source amplifier 122 is connected through the third dc blocking capacitor C4 to the second differential signal output by the balun differential signal conversion circuit 11, and the drain of the second gallium nitride MOS transistor M2 forms an amplified inverted differential output signal Vin-n.

as shown in fig. 4, the LED light emitter push-pull driving circuit 2 includes a push-pull circuit 21 composed of a third gan MOS transistor M3 and a fourth gan MOS transistor M4 for driving the LED, and an adjustable residual carrier extraction circuit 22 connected in parallel to the LED for limiting the speed of the emitter, wherein the gate of the third gan MOS transistor M3 constituting the push-pull circuit 21 is connected to the in-phase differential output signal Vin-p output from the signal processing circuit 1, the drain of the third gan MOS transistor M3 is connected to the first input voltage VLED1, the gate of the fourth gan MOS transistor M4 is connected to the inverted differential output signal Vin-n output from the signal processing circuit 1, the drain of the fourth gan MOS transistor M4 is connected to the second input voltage VLED2, the sources of the third gan MOS transistor M3 and the fourth gan MOS transistor M4 together constitute a driving signal output terminal connected to the LED, the output of the light emitting diode LED is driven and modulated, a first freewheeling diode D1 is connected between the drain electrode and the source electrode of the third gallium nitride MOS tube M3, and a second freewheeling diode D2 is connected between the drain electrode and the source electrode of the fourth gallium nitride MOS tube M4. The first input voltage VLED1 is greater than the second input voltage VLED2

The adjustable residual carrier extraction circuit 22 includes a fifth gallium nitride MOS transistor M5 and an and-or gate XOR connected to the gate of the fifth gallium nitride MOS transistor M5, the drain of the fifth gallium nitride MOS transistor M5 is connected to the input terminal of the light emitting diode LED through a tenth resistor, the source of the fifth gallium nitride MOS transistor M5 is connected to the ground terminal of the light emitting diode LED, the output terminal of the and-or gate XOR is connected to the gate of the fifth gallium nitride MOS transistor M5, one input terminal of the and-or gate XOR is directly connected to the Control signal output Control of the signal processing circuit 1, and the other input terminal of the and-or gate XOR is connected to the Control signal output Control of the signal processing circuit 1 through an RC circuit composed of a ninth resistor R9 and a fifth capacitor C5.

As shown in fig. 4, two differential signals obtained by the signal processing circuit are respectively input from the gates of two symmetrical gan MOS transistors M3 and M4, and the drains of the two gan MOS transistors M3 and M4 are switched into two voltages VLED1 and VLED2 with a voltage difference to control the LED to be in bright and dark transitions (VLED1 is greater than VLED 2). When the data signal is 1, the light emitting diode LED is in a bright state, the gallium nitride MOS tube M3 is turned on, and the gallium nitride MOS tube M4 is turned off; when the data signal is 0, the LED is in a dark state, and at this time, the gan MOS transistor M3 is turned off, and the gan MOS transistor M4 is turned on. Therefore, any gallium nitride MOS tube can be used as a switch, and only two states of conduction and disconnection are provided, so that extra power can not be consumed by light-dark conversion of the LED.

In order to avoid the crosstalk problem of light and dark paths of the LED due to asymmetric voltage of a drain end, a freewheeling diode is connected in parallel at the source and drain ends of two gallium nitride MOS tubes. When the gallium nitride MOS tube M3 is turned off and the gallium nitride MOS tube M4 is turned on, the freewheeling diode D1 is turned on and the freewheeling diode D2 is turned off; the generated reverse current can pass through the freewheeling diode D1 and be added with the leakage current of the gallium nitride MOS tube M4 to obtain the total current flowing through the light-emitting diode LED, so that the current signal modulated on the light-emitting diode LED forms overshoot when changing, the effect similar to pre-emphasis is achieved, and the speed of the transmitter is improved. Because of the large junction capacitance of the high-power light-emitting diode LED, the residual carriers cannot be discharged immediately when the LED is changed from bright to dark, and the speed of the whole transmitter is limited. The present invention thus designs an adjustable excess carrier extraction circuit as shown in fig. 4. The gallium nitride MOS tube M5 is connected in parallel with the light-emitting diode LED, when the light-emitting diode LED is bright or dark, a leakage path is provided for current carriers of the light-emitting diode LED and is quickly swept away, and a circuit structure consisting of a high-speed exclusive-OR gate and an RC is adopted to realize instant conduction of the gallium nitride MOS tube M5 when a signal is changed from 1 to 0 and then immediately close, so that the light-emitting diode LED is always in an inexact state.

As shown in fig. 5 and 6, the quiescent operating voltage V of the first common-source amplifier 121 and the second common-source amplifier 122 in the signal processing circuit 1 is set_Q1、V_Q2Is less than the turn-on voltage V of the third GaN MOS transistor M3 and the fourth GaN MOS transistor M4 constituting the push-pull circuit 21 in the push-pull driving circuit 2 of the LED light emitter_thIf the conduction angle of the light emitting diode LED is smaller than 90 degrees, the LED is in the BC class power amplification state.

According to the signal processing circuit 1, an input signal is converted into two paths of differential signals through the balun, then the two paths of differential signals are amplified through a common source amplifying circuit designed by the gallium nitride MOS tube, and then the two paths of differential signals are input into a push-pull type gallium nitride MOS tube driver. The static operating point voltage is as follows:

Only when the input signal is static working point voltage V_QGreater than the turn-on voltage V of the gallium nitride MOS tube_thIn this case, the gan MOS transistor is turned on. As shown in fig. 5, when the signal is amplified by the common source to the static operating voltage just V_QEqual to the turn-on voltage V_thThe positive half of the signal makes the GaN MOS tube be in an open state, and the conduction angle is just equal to 90 degrees at the moment, which is similar to a B-type power amplifier in radio frequency communication. To further improve system efficiency, the power amplification is made to resemble class B-C power amplification by reducing the conduction angle. As shown in fig. 6, by reducing the quiescent operating voltage V of the common source amplifier circuit_QAt this time, the positive half part of the signal only has the voltage greater than the turn-on voltage V_thThe part of the power amplifier enables the gallium nitride MOS tube to be in an open state, and the conduction angle is smaller than 90 degrees at the time of B-C power amplification. Therefore, the conduction angle is reduced, the overlapping time with the extraction of carriers is reduced, the dissipation power on the gallium nitride MOS tube is further reduced, and the efficiency of the whole system can be improved.