CN-121984460-A - Cascade and cross-coupling bandwidth transimpedance amplifier for visible light communication

CN121984460ACN 121984460 ACN121984460 ACN 121984460ACN-121984460-A

Abstract

The invention discloses a cascade and cross-coupling bandwidth trans-impedance amplifier for visible light communication, which adopts a fully differential topological structure, consists of a cascade enhancement type input stage, an active current source load and a cross-coupling bandwidth compensation network, and adopts a multistage cascade mode to construct an enhancement type feedback loop, wherein a multistage common source amplifier is connected in series in a feedback path of an input end; the current source is used for replacing the traditional resistance load, namely the load resistance of the common gate is replaced by the current source, and a pair of cross-coupled transistors are connected at the differential output end of the circuit, namely the grid electrodes and the drain electrodes of the transistors are cross-connected to form a positive feedback mechanism. The invention provides a novel RGC-TIA structure adopting optimized bias and cascade feedback, which simultaneously realizes high gain, wide bandwidth, good linearity and common mode rejection performance by breaking through voltage margin limitation.

Inventors

XIE SHENG
Zhu Bochuan

Assignees

天津大学

Dates

Publication Date: 20260505
Application Date: 20260123

Claims (5)

1. A cascade and cross-coupling bandwidth transimpedance amplifier for visible light communication is characterized in that the amplifier adopts a fully differential topology structure and consists of a cascade enhancement type input stage, an active current source load and a cross-coupling bandwidth compensation network, An enhanced feedback loop is constructed in a multistage cascade mode, wherein a multistage common source amplifier is connected in series in a feedback path of an input end; Replacing a traditional resistance load with a current source, namely replacing a load resistance of a common grid stage with the current source; a pair of cross-coupled transistors are connected at the differential output of the circuit, with the gates and drains of the transistors being cross-connected to form a positive feedback mechanism.
2. The cascode and cross-coupled bandwidth transimpedance amplifier for visible light communication according to claim 1, wherein the circuit structure of the amplifier comprises a left half cascode feedback unit, a right half cascode feedback unit, and a cross-coupling unit.
3. The cascode and cross-coupled bandwidth transimpedance amplifier for visible light communication according to claim 2, wherein the left side cascode feedback unit is: The source electrode of the first transistor is connected with the input end IN 1 , the drain electrode of the first bias tube, the drain electrode of the first feedback tube and the source electrode of the first cross coupling tube, the grid electrode of the first transistor is connected with the bias voltage V b , the drain electrode is connected with one end of the first resistor and the grid electrode of the second transistor, the drain electrode of the first bias tube is connected with the input end IN 1 , the source electrode of the first transistor, the source electrode of the first cross coupling tube and the drain electrode of the first feedback tube, the grid electrode of the first bias tube is connected with the bias voltage V b1 , and the source electrode is grounded; The source electrode of the second transistor is connected with the drain electrode of the second bias tube, the gate electrode of the second transistor is connected with one end of the first resistor, the drain electrode of the first transistor and the drain electrode of the first cross coupling tube, the drain electrode of the second transistor is connected with one end of the second resistor and the gate electrode of the third transistor; The source electrode of the third transistor is connected with the drain electrode of the third bias transistor, the grid electrode of the third transistor is connected with one end of the second resistor and the drain electrode of the second transistor, the drain electrode of the third transistor is connected with one end of the third resistor, the grid electrode of the first feedback transistor and the grid electrode of the fourth transistor, the grid electrode of the third bias transistor is connected with bias voltage V b4 , and the source electrode of the third bias transistor is grounded; The other end of the third resistor is connected with a power supply, the source electrode of the first feedback tube is grounded, and the grid electrode of the first feedback tube is connected with one end of the third resistor, the drain electrode of the third transistor and the grid electrode of the fourth transistor; The drain electrode of the fourth transistor is connected with one end of the fourth resistor, the grid electrode of the second cross coupling transistor and the first output end, the source electrode of the fourth transistor is connected with the drain electrode of the fourth biasing transistor, the other end of the fourth resistor is connected with a power supply, the grid electrode of the fourth biasing transistor is connected with a biasing voltage V b3 , and the source electrode of the fourth biasing transistor is grounded.
4. The cascode and cross-coupled bandwidth transimpedance amplifier for visible light communication according to claim 2, wherein the right half cascode feedback unit is: The source electrode of the fifth transistor is connected with the input end IN 2 , the drain electrode of the fifth bias tube, the drain electrode of the second feedback tube and the source electrode of the second cross coupling tube, the grid electrode of the fifth transistor is connected with the bias voltage V b , the drain electrode of the fifth transistor is connected with one end of the fifth resistor and the grid electrode of the sixth transistor, the drain electrode of the fifth bias tube is connected with the input end IN 2 , the source electrode of the fifth transistor, the source electrode of the second cross coupling tube and the drain electrode of the second feedback tube, the grid electrode of the fifth bias tube is connected with the bias voltage V b1 , and the source electrode is grounded; The source electrode of the sixth transistor is connected with the drain electrode of the second bias tube, the gate electrode of the sixth transistor is connected with one end of the fifth resistor, the drain electrode of the fifth transistor and the drain electrode of the second cross coupling tube, the drain electrode of the sixth transistor is connected with one end of the sixth resistor and the gate electrode of the seventh transistor; the source electrode of the seventh transistor is connected with the drain electrode of the third bias tube, the grid electrode of the seventh transistor is connected with one end of the sixth resistor and the drain electrode of the sixth transistor, and the drain electrode of the seventh transistor is connected with one end of the seventh resistor, the grid electrode of the second feedback tube and the grid electrode of the eighth transistor; the source electrode of the second feedback tube is connected with GND, and the grid electrode of the second feedback tube is connected with one end of the seventh resistor and the drain electrode of the seventh transistor; The drain electrode of the eighth transistor is connected with one end of the eighth resistor, the grid electrode of the first cross coupling transistor and the second output end OUT 2 , the source electrode of the eighth transistor is connected with the drain electrode of the fourth bias transistor, and the other end of the eighth resistor is connected with a power supply.
5. A cascode and cross-coupled bandwidth transimpedance amplifier for visible light communication according to claim 2, wherein the cross-coupling unit is: The gate of the first cross-coupled tube is connected across the second output terminal OUT 2 and the gate of the second cross-coupled tube is connected across the first output terminal OUT 1 .

Description

Cascade and cross-coupling bandwidth transimpedance amplifier for visible light communication Technical Field The invention relates to the field of amplifiers, in particular to a cascade and cross-coupling bandwidth transimpedance amplifier for visible light communication. Background With the rapid development of the fifth generation mobile communication and internet of things technology, wireless data traffic is undergoing explosive growth, which places unprecedented high demands on bandwidth, speed and security of the communication technology. Therefore, conventional radio frequency communication technologies are facing challenges such as spectrum resource shortage, electromagnetic interference, and information security. The LED illuminating device has the advantages of no need of spectrum permission, no electromagnetic interference, strong information safety and the like, can fully utilize the existing LED illuminating device, ensures that the visible light communication becomes a beneficial supplement of the traditional radio frequency communication technology, and has great application value in specific scenes such as intelligent home, indoor positioning, underwater wireless communication and the like, thereby becoming a research hot spot in academia and industry. Along with the continuous reduction of the feature size of the silicon-based CMOS process, the process maturity is continuously improved, and the guarantee is provided for the construction of high-speed and low-power consumption visible light communication integrated circuit design. Therefore, the visible light communication chip designed based on the standard CMOS process is one of the research hotspots in the field of optical communication. As a core component of the visible light communication system, the optical receiver is responsible for converting an optical signal carrying information into an electrical signal and performing a series of processes. The transimpedance amplifier (TIA) located at the forefront of the receiver is the most critical module in the whole signal chain, and its performance directly determines the receiving sensitivity, data transmission rate and overall power consumption of the visible light communication system. The TIA needs to convert the weak current signal generated by the photodiode into a voltage signal with high fidelity, and overcomes the bandwidth limitation of the large capacitance of the photodiode, which requires that the transimpedance amplifier have excellent characteristics of high gain, wide bandwidth, low noise, and the like. To meet the above requirements, industry and academia have devised a variety of TIA topologies. Among them, the regulated cascode (RGC) structure is considered as the most competitive solution at present because it can effectively reduce input impedance through local feedback, expand bandwidth while maintaining high gain. However, with the shrinking of semiconductor process nodes and increasing of operating rates, conventional RGCs and their derivative structures also face many challenges in practical applications. Xie Sheng et al (CN 201810581789.2) propose a pseudo-differential structure regulated cascode transimpedance amplifier with high bandwidth, which solves the problem of bandwidth limitation of large capacitance, but the gain is not high, limiting the signal-to-noise ratio and sensitivity of the circuit. To break through the bandwidth bottleneck, hongli et al (CN 202323402458.3) apply on-chip inductive peaking techniques to visible light integrated circuit designs, but they occupy a large chip area and are prone to electromagnetic interference. In addition, DIAAELDIN et al [1] propose a transimpedance amplifier of differential structure that utilizes cross coupling for capacitance neutralization, but the capacitance neutralization technique can only partially cancel the miller capacitance, cannot completely eliminate the total parasitic capacitance at the node, and is more sensitive to process deviation. Abdollahi et al [2] propose an improved RGC structure that reduces the input impedance by introducing an auxiliary amplifier in the feedback loop, but this circuit structure is not suitable for advanced process nodes with low supply voltages, because the transistors therein are difficult to operate in the saturation region, thus limiting the linearity of the circuit. In summary, although the performance of the transimpedance amplifier is optimized to some extent by the conventional RGC and its improved structure, it is difficult for the prior art to break through the limitation of power consumption and voltage margin under the environment of increasingly lower power supply voltage of the standard CMOS process, and simultaneously, the requirements of the next generation of high-speed visible light communication on the comprehensive severity of broadband, high sensitivity and high linearity are satisfied. Reference to the literature [1]Diaaeldin A, Mohamed A. A Diff