Low Power Non-Recursive Decimation Filters

This work proposes low power non-recursive decimation filters in a GSM (global system for mobile communication) and UMTS (universal mobile telecommunications system) dual mode sigma delta ADC. The proposed technique is an alternative to the standard CIC (Cascaded Integrator-Comb) approach with a decimation factor of m-th power of two and m-th power of three. 70% to 80% power consumption can be saved by the non-recursive structure compared to the Hogenauer CIC architecture. More research is done to find the break-even point of silicon area for non-recursive and recursive architectures. A low power decimation filter chip for a UMTS and GSM dual mode sigma delta A/D converter is fabricated in 0.35◻m CMOS (complementary metal-oxide- semiconductor) and consumes 4.72 mW in GSM and 5.54 mW in UMTS mode, both at Vdd=2.5V.