A Switched-Capacitor, Integrator-Multiplexing, Second-Order Delta-Sigma Modulator Featuring a Single Differential Difference Amplifier for Portable EEG Application

We present a novel switched-capacitor, integrator-multiplexing, second-order delta-sigma modulator (DSM) featuring a single differential difference amplifier (DDA). Power consumption is low and resolution is high when this DSM is used for portable electroencephalographic applications. A single DDA (rather than a conventional operational transconductance amplifier) with appropriate switch and capacitor architectures is used to create the second-order switched-capacitor DSM. The configuration ensures that the resolution is high. The modulator was implemented using a standard 180nm complementary metal-oxide-silicon process. At a supply voltage of 1.8V, a signal bandwidth of 250Hz and a sampling frequency of 200kHz, simulations demonstrated that the modulator achieved an 82dB peak signal-to-noise-distortion ratio and an effective number of bits of 14.