A Type Of High Frequency Transimpedance Amplifiers Design

Continuous growth in data communications network traffic triggered the rapid construction of fiber-optic networks, bandwidth and higher rates for people with infinite demand, and promote a large number of fiber-optic communications research, companies and research institutes have invested a lot of manpower and material in them, and the optical transmitter and receiver become one of the research focus. As a core component of optical receiver, the transimpedance amplifier is in a rapid development progress in recent years, so to speak, the performance of transimpedance amplifier in the optical receiver determines the performance of optical receiver. Therefore, all companies gave a high attention in this respect, and expect to design higher performance and also better be able to work at a higher transmission rate transimpedance amplifier.This thesis presents a new high-gain transimpedance amplifier using BJT technology. The goal is to amplify 1μA 300 MHz small signal AC current to a 40 mV AC voltage signal, and drive a 1.5K? resistor and 3pF capacitor load in parallel.To simplify the circuit with increasing the use of flexibility, and reduce the risk of chip flow, the amplifier is divided into two levels in the design: the first level is a pre-I-V conversion amplifying circuit, its function is to amplify 1μA small signal to 2mV, achieve I-V conversion; second level is a voltage amplifier circuit, the function is to amplify the voltage from 2mV to 40 mV or more, and meet the bandwidth requirements of the cascade, and use 100 pF capacitor coupling between the two levels.This paper focuses on how to implement the BJT process of transimpedance amplifier. During the design of high frequency transimpedance amplifier, analyze and understand the architecture and properties of RF transmitter and optical receiver, after considering the design requirements and indicators, compromise the gain, bandwidth, noise, sensitivity, voltage, redundancy and other performance to a reasonable state, proposed a high-gain controllable BJT transimpedance amplifier circuit. At the beginning of this thesis, introduced less current mode circuits and RF receiver and transmitter, analyzed current mode circuits and their characteristics and BJT RF transmitter and ultra-wideband receiver; then introduced transimpedance amplifier and gain control technology, analyze BJT transimpedance amplifier circuit structure and it’s technology; then introduced transimpedance amplifier bandwidth expansion technology. After compared the various technologies then selected the appropriate bandwidth expansion technology; finally expounded BJT transimpedance amplifier design, circuit topology, structure and circuit simulation analysis and layout drawing.By simulation verification, obtained the most optimum design. The design is a simple circuit structure, and meets design indicators in performance part too. Reduces the risk in the chip flow and greatly reduces the cost of the circuit too, with a very bright market development and application space.