Two op-amps third-order sigma-delta modulator with 61-dB SNDR, 6-MHz bandwidth and 6-mW power consumption

This low-power Sigma Delta modulator targets the DVB-H requirements and achieves about 10 bit with 6-MHz signal band. Suitable topological modifications enable the realization of a third order modulator with two op-amps. Moreover, a technique for swing reduction of the last op-amp strongly reduces the number of comparators in the quantizer. The power reduction techniques limit the consumption to 6.18 mW, thus yielding a FoM of 0.58 pJ/conversion. The area of the circuit, fabricated with a 0.18-mu m analog CMOS technology, is 0.32 mm(2). Experimental measurements confirm the behavioral study made accounting for the op-amps limitations.