A balanced CMOS OpAmp with high EMI immunity

In this paper a balanced CMOS operational amplifier which has higher electromagnetic interference (EMI) immunity compared to a double differential amplifier and standard Miller operational amplifier, has been introduced. The proposed amplifier has better EMI immunity, from 1 MHz - 1 GHz, by keeping specifications such as gain, -3 dB bandwidth, phase margin, power supply rejection and unity gain frequency same as in the Miller operational amplifier. Analysis and simulation results are compared when an EMI signal of 1.1 Vpp applied at the input terminal. The simulation results show that the EMI-induced offset voltage is lesser over a wide range of frequencies for the proposed amplifier.