A CMOS TIA with Active Shunt-Shunt Feedback and Passive Loop Gain Boosting

Passive loop gain boosting is proposed to simultaneously reduce the power consumption and the input-referred noise of an active shunt-shunt feedback CMOS transimpedance amplifier (TIA). The use of a four-phase charge pump introduces passive voltage gain that boosts the loop gain with minimum increase of the current consumption of the circuit. The increased loop gain allows to reduce the bias current of the amplifier, while keeping the input resistance constant. This implies a reduction of the input-referred noise of the circuit and, overall, a decrease in the power consumption of the TIA. The proposed technique is validated by transistor-level simulations on a design example in a 22nm CMOS technology.