A CMOS pulse density modulator for high-resolution A/D converters

A high-performance pulse density modulator (PDM) has been fabricated using a 3.5-/spl mu/m CMOS silicon gate technology. The PDM comprises all the analog circuitry needed for an interpolative A/D converter. The PDM can be operated at sample rates of up to 12 MHz and offers a SNR of 80 dB over a baseband of 20 kHz, which corresponds to 13-bit equivalent A/D resolution.