Systematic Design Methodology of a Wideband Multibit Continuous-Time Delta-Sigma Modulator

Abstract EN

Systematic design of a low power, wideband and multi-bit continuous-time delta-sigma modulator (CTDSM) is presented.

The design methodology is illustrated with a 640 MS/s, 20 MHz signal bandwidth 4th order 2-bit CTDMS implemented in 0.18 µm CMOS technology.

The implemented design achieves a peak SNDR of 65.7 dB and a high dynamic range of 70 dB while consuming only 19.7 mW from 1.8 V supply.

The design achieves a FoM of 0.31 pJ/conv.

Direct path compensation is employed for one clock excess loop delay compensation.

In the feedforward topology, capacitive summation using the last opamp eliminates extra summation opamp.