High Speed Front-end Amplifier Design For Optical Receiver Of Optical Interconnection

With the increasing of Integrated Circuits'Frequency, many problems appear, such as attenuation, cross-talk and impedance matching. It is very difficult to transmit electrical signals on PCB whose bit rate reached 10Gbps or above,which has become the bottleneck of the system performance. Compared to the electrical interconnection, optical interconnection is a good candidate due to its advantages of high bandwidth,low attenuation, no cross-talk, no impedance matching and low Electromagnetic Interference(EMI).In the building blocks of an optical interconnect system, the pre-amplifier and the main amplifier are the critical parts.The performance of a preamplifier has great effect on the performance of an optical receiver. Transimpedance pre-amplifiers are widely used in the high speed optical transmission systems. The preamplifier exploits the Regulated Cascode(RGC) configuration as the input stage, which isolates the large input parasitic capacitance including photodiode capacitance from the bandwidth determination.An Automatic Gain Control (AGC) amplifier or a limiting amplifier is generally used to realize the main amplifier. The latter was chosen to realize the main amplifier in our design since it has the features of simple topology, few areas and low power consumption. A differential common source amplifier is used as the basic amplifier. The direct-coupled technology is employed between different amplifier to reduce the power dissipation.The monolithic integrated front-end amplifier whose processing speed achieved 2.5Gbps was designed in SMIC 0.18μm CMOS technology. On the basis of theory analysis and design optimization, the circuit achieves high performance of gain, bandwidth and power dissipation.This paper firstly describe the circuit design and then introduce the layout of these circuits. The simulation results from Cadence Virtuoso suggest that the design achieves the needed speed and power consumption.