A 0.5V 94dB SNR CT-ΣΔ modulator for implantable and portable biomedical devices

A CT-ΣΔ Modulator having very low power dissipation is presented in this paper. The device was implemented on 0.35μm CMOS technology and it consists of a second order modulator and a decimation stage based upon a finite impulse response (FIR) filter. The modulator and the FIR stages supply voltages are 0.5V and 1V, respectively. The modulator measured characteristics are: signal to noise ratio (SNR) of 94.2dB, effective number of bits (ENOB) of 15.35 bits, integral no linearity (INL) of +0.34/-2.3 LSB, differential no linearity (DNL) of +0.78/-0.62 LSB without missing a single code, and a power dissipation of only 7μW. An exhaustive literature review revels that this is the first ADC operating at 0.5V, having a 0 to 100Hz bandwidth (BW) and showing a SNR greater than 94dB. This ADCs performance is suitable for very low power biomedical applications such as implantable and portable devices.