Efficient IIR switched-capacitor decimators and interpolators

The IIR switched-capacitor decimators and interpolators proposed in this paper are based on the polyphase decomposition of an M-th band IIR lowpass filter, and uses first- and second-order allpass switched-capacitor filters as basic building blocks, which operate at the lower sampling rate, reducing power consumption, capacitance spread and total capacitance area. The resulting switched-capacitor network has low sensitivity with respect to capacitance ratio errors, specially in the pass-band, where very low sensitivity is guaranteed by using structurally allpass filters. These properties have been verified by computer based sensitivity analysis, and an illustrative design example, considering realistic specifications for video communication applications, included in the paper, along with comparisons with other approaches reported in the literature. Laboratory results obtained with a prototype filter are shown as well.