Bulk-Driven CMOS Amplifier With High EMI Immunity

This paper presents a bulk-driven CMOS amplifier with high immunity to electromagnetic interference (EMI). The approach is based on a bulk-driven input stage of MOSFET, thereby providing a low-voltage realization of a gate-driven stage. The bulk-driven amplifier includes the positive feedback, an input voltage drop, and dual input-stage symmetrical topology to improve the equivalent transconductance, dc linearity, and ac performance. As demonstrated by the measurements, the dc offset of the proposed amplifier is less than 70 mV, the measured PSD is about -66 dBm with 1 -V_pp EMI conveyed. The amplifier chip is implemented using a 0.35 μm standard CMOS process with a 1-V power supply.