Design Of 28Gb/s Front-end Amplifier Based On 0.13?m SiGe BiCMOS Technology

In recent years,with the rapid development of information technology industry,optical fiber communication has gradually become the mainstream communication mode of urban backbone network by virtue of its superior performance.In order to cope with the emergence of new applications and the exponential growth of data volume,standard organizations,communication equipment manufacturers and scientific research institutions are actively carrying out research work on next-generation optical communication system technologies.The main research object of this paper is the optical receiver front-end amplifier circuit,which can convert the weak current signal output from the photodetector into a voltage signal and amplify it to a certain amplitude.Front-end amplifiers are an important part of fiber-optic communication systems and largely determine the performance of optical receiver systems.Therefore,the research work in this paper has important significance and value.The front-end amplifier circuit of 28Gb/s optical receiver is designed based on the process of GF0.13?m SiGe BiCMOS in this paper.The main performance indicators considered include noise,transimpedance gain,-3dB bandwidth and power consumption.The structure of the system consists of a transimpedance amplifier,an automatic gain control circuit,a single-ended-dual-ended conversion circuit,an output buffer and a current monitoring circuit.The transimpedance amplifier is composed of a cascode structure as the input stage,and the feedback resistance is connected across the input and output terminals.The advantage of this structure is that the circuit is simple,the input impedance is small,the large bandwidth and low noise are easy to achieve,and it's easy to compromise and balance among various indicators.The automatic gain control stage controls the transimpedance gain through a feedback loop.The main function of the current monitoring circuit is to provide a bias voltage to the cathode of the photodiode and to observe the magnitude of the input current externally.The output buffer is used to drive and match the off-chip load.The overall layout size of the 28Gb/s front-end amplifier circuit designed in this paper is 836?m ×574?m.The simulation results show that the bandwidth of-3dB can reach 20.3 GHz and the dynamic range of transimpedance gain is 43.9~55.2 dB.The dynamic range of input is 40?A-1mA while the equivalent input noise current is 4.31?A.The total static power consumption is 122.45 mW.The eye diagram is of good quality and the data jitter is less than 0.1UI.The post-simulation results of the overall indicators meet the expected index requirements,and have a certain margin.