A 400 mV, 17.79 nW Floating-Inverter-DIGOTA-Based First-Order Continuous-Time ΣΔ Modulator in 180 nm

This paper presents a low-power first-order continuous-time sigma-delta (CT-Σ Δ ) modulator featuring a continuous-time integrator based on a fully differential floating-inverter-input digital operational-transconductance-amplifier (FI-DIGOTA). From post-layout simulations in 180nm CMOS, the proposed CT-Σ Δ modulator operates at 400mV supply with a total power consumption of 17.79nW and achieves a signal-to-noise-and-distortion ratio (SNDR) of 50.92dB, a spurious-free dynamic range (SFDR) of 55.14dB, and an effective number of bits (ENOB) of 8.166bit across 500Hz bandwidth at 100 oversampling ratio (OSR), resulting in a peak Schreier figure-of-merit (FOM_SCh) of 155.4dB. Post-layout simulations across process corners and Monte Carlo simulations reveal consistent operation across process, supply voltage and temperature variations, and confirm its suitability to energy-constrained IoT sensor interfaces.