Design Of Front-end Amplifier For 10Gbps Optical Receiver Based On 0.18?m SiGe BiCMOS Technology

With the rise of big data,internet of things?IOT?,multimedia,cloud computing etc applications,the demand from human beings for data communication information grows exponentially.This requires the speed,distance,capacity and other performance of data communication to be improved accordingly.However,the traditional electrical interconnection has the disadvantages of large loss and small capacity,which cannot meet already the needs of data communication.Optical interconnection and optical fiber communication have gradually replaced electrical interconnection because of its high speed,large capacity,strong anti-interference and low loss etc advantages,becoming the mainstream of data communication nowadays.As an important part of the receiving end in the optical fiber communication system,the front-end amplifier of the optical receiver converts the weak optical current into the voltage signal and amplifies it as reliably as possible,making sure it can be processed by the subsequent logic circuits.Its performance determines the performance of the optical receiver to a great extent.Based on the theoretical analysis,this paper designs a 10Gbps front-end amplifier of optical receiver with low noise and wide dynamic range.The front-end amplifier circuit mainly includes transimpedance amplifier,two-stage variable gain amplifier,automatic gain control loop,DC offset cancellation loop and buffer output circuit.In order to obtain excellent noise performance,a shunt-shunt feedback structure is used in the transimpedance amplifier.The two-stage variable gain amplifier is realized based on the Gilbert cell.And combined with DC offset cancellation loop,it greatly widens the input dynamic range.The automatic gain control circuit is realized by a smart and portable peak detector,which reduces the power consumption and complexity.Finally,the buffer circuit uses the technology of capacitance degradation to expand the bandwidth.Based on the 180nm SiGe BiCMOS process,the layout of the chip circuit is drawn,with an overall area of 764?m×540?m.The simulation results show that the gain tuning range of the front-end amplifier is 25.2?80.6d B?,and the-3d B bandwidth is stable at 7.4?9 GHz.The equivalent input noise current of the circuit is14.6?A_rms,with the average equivalent input noise current density of 16.9p A/?Hz.All the whole circuit is powered by a single 3.3V power supply,and the static power consumption is 166m W,which meets the demand of 10Gbps optical communication.