Efficient design of integrated switched-capacitor decimation filters

The infinite-impulse response (IIR) switched-capacitor (SC) decimation filter scheme proposed in this brief is based on the polyphase decomposition of an Mth band IIR low-pass filter, and uses first- and second-order all-pass SC filters as basic building blocks, operating at the lower sampling rate, resulting in reduced power consumption, capacitance spread, and capacitance area. The SC realization has low sensitivity with respect to capacitance ratio errors, especially in the passband, due to the use of structurally all-pass filters. These properties have been verified by computer analysis. An illustrative design example is included, along with comparisons with other approaches reported in the literature. Laboratory results obtained with a prototype filter are shown, as well.