A micropower current-mode sigma-delta modulator for biomedical applications

This paper presents the design of a low power second-order continuous-time sigma-delta modulator for biomedical applications. The loop filter of this modulator has been implemented based on the nonlinear transconductance-capacitor (G
_m
-C) by employing current-mode technique. The nonlinear transconductance uses floating gate MOS (FG-MOS) transistors that operate in weak inversion region. The proposed modulator features low power consumption (80 uW), low supply voltage (1 V) and 62 dB dynamic range. Simulation results by HSPICE confirm that it is very suitable for low power biomedical instrumentation designs.