Bandwidth Extension And Signal Detection In 1.25Gb/s Limiting Amplifier

With the development of technology and Internet, optical fiber communication technology had been invented to achieve higher speed data exchange, and rapidly develop in recent years. China has established a national fiber optical communication system now. The limiting amplifier is a key part of optical receiver in the system, it determines the performance of whole system, so it's great significant to research and develop with independent intellectual property rights of limiting amplifier.In this thesis, multi-stage amplifier module and input signal detection module were designed based on the SMIC 0.18μm CMOS technology. A multi-stage circuit was designed to obtain enough gain, while used the improved Cherry-Hopper structure to extend the bandwidth. Every stage had different circuit structure which could reduce the chip area size. The input signal detection module was designed based on limited resistance of non-ideal current source. Detection module would shutdown output buffer module to reduce power consumption and impact of noise when input signal amplitude didn't meet requirement. Hysteresis effect was designed to reduce the malfunction this module .The simulation results by Hspice indicated that the amplifier module had a 40dB gain, 932MHz bandwidth and a minimum input dynamic range with 4mVp-p, which could meet the application requirements of STM-8(1.25Gb/s) in optical fiber communication system. The detection module had 1.9dB hysteresis window, better than the design requirements of 1.5dB.Layout design was critical so the paper introduced parasitic parameters which would impact the circuit performance and some design skills, then gave a complete territory of limiting amplifier at last.