Exploring the noise limits of fully-differential micro-watt transimpedance amplifiers for Sub-pA/yHz sensitivity

This paper explores the noise performance limits of the differential configurations of differential transimpedance amplifiers (TIAs), which serve as a current detection front-end and converts signals for backend signal processing. TIA is one of the most frequent module adopted in biological and environmental sensing such as hall sensors and DNA synthesis detection, which require noise density down to sub-pA/√Hz with micro-watt power consumption so detailed analysis on the noise performance is required. The noises for three different TIAs, including the common-gate topology, op-amp based resistive feedback and capacitive feedback, have been investigated and simulated. Among them, op-amp based capacitive feedback, which bases on integration of input current, displays the lowest noise and best performance. Simulated in 180 nm CMOS process, the capacitive feedback technology shows an input-referred noise of 16 fA/√Hz (80 fA/√Hz) at 10 kHz (100 Hz), featuring it a promising solution for current detection.