A RGC-based,low-power,CMOS transimpedance amplifier for 10Gb/s optical receivers

ABSTRACT

In this paper, a new low-power transimpedance amplifier (TIA) based on a modified Regulated Cascode (RGC) circuit structure followed by a closed-loop post-amplifier is proposed for 10 Gb/s applications. The main objective of this work is to reduce the power consumption while, the frequency bandwidth of the proposed amplifier is increased considerably. The booster of a conventional RGC is modified by a cascoded transistor and its effect on the performance of the circuit is studied mathematically, which are verified by simulations. The bandwidth extension is occurred due to increasing the gain of the booster amplifier in the RGC stage, which isolates further the input capacitance and results in a reduced input resistance value hence, a higher input pole frequency is obtained in comparison with other conventional RGC structures. On the other hand, by using an active inductive peaking technique, the frequency of the output pole is also increased which results in a further extension of the frequency bandwidth for the proposed circuit. The proposed TIA is simulated using 90 nm CMOS technology parameters, which shows a 50.5 dBΩ transimpedance gain, 7.3 GHz frequency bandwidth and 1.22 µA_rms input referred noise value for only 1 mW of power consumption at 1.2 V supply voltage.