Chopper-Stabilized Low-Noise Multipath Operational Amplifier With Dual Ripple Rejection Loops

This brief presents a chopper-stabilized low-noise multipath operational amplifier with dual ripple rejection loops. The multipath amplifier scheme has a lower noise and a wider bandwidth than the conventional chopper amplifiers. The dual ripple rejection loops are proposed to effectively attenuate the offset and low-frequency noise components. The dual ripple rejection loops are implemented using a feedback low-pass filter (LPF) for AC coupling and a floating high-pass filter (HPF) for additional low-frequency rejection with a fast common mode response. The amplifier is fabricated using a 0.18-${\mu }\text{m}$ CMOS process with an active area of 4.92 mm(2). The input referred noise level is 6.62 nV/$\surd $ Hz, and the total current consumption is 117.2 ${\mu }\text{A}$ with a 1.8 V power supply.