A Power-Efficient 13-Tap FIR filter and an IIR Filter Embedded in a 10-bit SAR ADC

This paper presents a power-efficient 13-tap finite impulse response (FIR) filter, and an infinite impulse response (IIR) filter embedded in a 10-bit SAR ADC. Using the capacitive DAC array, the IIR filter is inherently realized without DC attenuation through sharing charge in the capacitors between the FIR filter and the SAR ADC periodically. The IIR filtering performance can be optimized further through the time-interleaved technique and introducing two additional phases. Compared with a 15-tap FIR filter, the attenuation at the cutoff frequency is enhanced by 9dB theoretically. A prototype filter in 40nm CMOS occupies an active area of 0.067mm(2), consumes 38uW with 1MHz bandwidth, and obtains >42.2dB out-of-band suppression when operated at 40MS/s.