Design And Simulation Of CMOS Pre-amplifier For Optical Receiver

With the development of the world, people exchange more and more data. So we put forward higher requirements for high speed communication system. High speed, large capacity optical fiber communication system has become the only choice for today’s high speed communication network. In the optical receiver system, the pre-amplifier is a very import part. Because it affects the whole system performance such as speed, sensitivity, and signal-to-noise ratio.In this paper, we research the pre-amplifier used in optical receiver. Firstly, this paper introduces the research background, the research status at home and abroad. Then this paper introduces optical fiber communication system, optical receiver and photodetector. This paper analyzes the three types of pre-amplifier:low-impedance pre-amplifier, high-impedance pre-amplifier, trans-impedance pre-amplifier. The trans-impedance amplifier is the best choice for this paper because it has the characteristics of low input impedance, large dynamic range, high gain, large bandwidth, low noise. Then this paper analyzes the noise characteristics and the basic principles of trans-impedance amplifier. Besides, this paper analyzes the four different circuits of trans-impedance pre-amplifier. This paper simulates the four circuits. Finally, this paper chooses RGC form trans-impedance pre-amplifier as the design.In this paper, the design of the trans-impedance pre-amplifier is divided into four modules:RGC form trans-impedance pre-amplifier, single to differential circuit, post amplifier, the output buffer circuit. The RGC form trans-impedance pre-amplifier is optimized to expand bandwidth by using the inductive shunt peaking technology and inductive series peaking technology. The inductive shunt peaking technology is verified by simulation. The single to differential circuit is designed to meet the input requirements of the main amplifier. Because RGC form trans-impedance pre-amplifier needs to meet the requirement of bandwidth, noise performance, the gain can’t be too high. Therefore, this paper optimizes the overall structure. The post amplifier is cascaded to boost gain. The output buffer circuit is to increase the driving ability of the circuit. This paper simulates each modules.In this paper, the design of the optical receiver trans-impedance pre-amplifier uses 0.5μm CMOS technology library for overall simulation. The results show that the trans-impedance pre-amplifier has 2GHz bandwidth,66.63dB Ω trans-impedance gain, 23.37pA/sqrt(Hz) equivalent input noise. The designed pre-amplifier meets requirements of the 2.5Gbit/s optical receiver.