A multibit continuous time sigma delta modulator with successive-approximation quantizer

This paper discusses the design of a multibit sigma-delta modulator using a continuous time (CT) loop filter and a successive approximation (SA) A/D converter as multibit quantizer instead of the usual flash converter. This results in reduced circuit complexity as well as lower power dissipation and area. Measured results of a second order CT modulator with three bits quantizer show 58 dB SNR and 120 muW power dissipation with an OSR of 16 and a power supply equal to 1.5 V