A Fully Differential Switched Capacitor Amplifier with a Two-Stage Folded-Mesh Class AB Operational Amplifier in a 22 nm FD-SOI CMOS Process

In this paper, we present a fully differential switched capacitor amplifier with a two-stage folded-mesh class AB operational amplifier, where an internal regulator is employed. The operational amplifier has open-loop DC gain of 147 dB, unity gain bandwidth of 59 MHz, and phase margin of 68 degree at 5 pF load in simulation. 54 dB power supply rejection on the outputs is achieved at 100 kHz, thanks to the internal regulator. The switched capacitor amplifier has voltage gain of 8 and SNDR (Signal-to-Noise and Dynamic Range) of 76.5 dB and SFDR (Spurious-Free Dynamic Range) of 77.3 dBc are obtained by FFT (Fast-Fourier Transform) spectrum simulation when a 95 mVpeak sinusoidal signal of 12.945 kHz is applied. The switched capacitor amplifier is implemented in a 22 nm FD-SOI (Fully Depleted Silicon-On-Insulator) process. It consumes 2.45 mW at a sampling clock of 104.2 kHz and occupies an active die area of 0.0946 mm
²
.