Design of low-voltage CMOS amplifier with high EMI immunity

A low-voltage bulk-driven amplifier with high electromagnetic interference (EMI) immunity is proposed. To improve EMI immunity of the bulk-driven amplifier, a partial positive feedback enhances its equivalent transconductance, an input voltage-drop structure modifies its DC nonlinearity, and a dual input-stage ensures the desired AC feature. Theoretical analysis and simulation results for EMI robustness are presented and compared with the classical bulk-driven amplifier: the offset voltage is less than 50mV over the whole considered frequency range.