Design Of Ultra-High Speed Optical Receiver Front-End Amplifier In 0.13?m BiCMOS Technology

In recent years,with the rapid development and innovation of fiber optic business,the demand for high-speed optical fiber transmission system has become more urgent.The performance optical receiver has a crucial impact on the entire fiber optic communication systems,and as the key module of optical receiver,the performance of the front-end amplifier amplifier has a decisive influence on the performance of the optical receiver.Front-end amplifier located after the photodetector,the photodetector converts the optical signal to current signals,and the front-end amplifier is utilized to convert the current signal generated by the photodetector into voltage signals and amplified to a certain amplitude.The design of front-end amplifier focuses primarily on the following parameters:transimpedance gain,bandwidth,noise,input current dynamic range,and gain dynamic range.The front-end amplifier includes the transimpedance amplifier(TIA),AGC circuit and an output buffer circuit.The role of theTIA is to convert the current signals generated by the photodetector into voltage signals.The pseudo-differential common-base feedforward is employed in TIA.It has very small input impedance,and suits for high speed optical receiver.Since the light intensity received by the receiver is varied,the amplitude of the current signal generated by the photodetector is also varied.So in order to amplify the signals to a certain amplitude,the AGC is needed to change the gain according to the magnitude of the input current signals.The variable gain amplifier(VGA)provides the variable gain.The VGA is modified from the Gilbert Cell.The capacitance degradation technology is used to expand the bandwidth of the output buffer circuit.The front-end amplifier is implemented in the IBM 0.13 ?m BiCMOS process,and the layout is designed in this process,the area of the whole circuit is about 865?m×593?m.From the simulation results,the gain-controlled range of the front-end amplifier is from 36.4dB? to 75.4dB?.The output voltage swing is between 150mV and 250mV while the input current dynamic range from 40?A to 1.5mA.The power dissipation is 450mW with 3 V and 4V supply voltage.The simulation results show that the design of front-end amplifier is suitable for 56GB/s optical fiber communication systems.