A novel fully programmable switched-current IIR filter

A fully programmable switched-current IIR filter using switched-current delay-multiplies units is described. The characteristics of the filter are fully programmable by simply changing the ratios of the coefficient transistors. To reduce the effect of non-ideal characteristics of MOS transistors, a high-performance differential switched-current memory cell is used as a basic building block. To reduce the chip area and maintain the required accuracy of the coefficients, an array consisting of three different sizes of transistors is designed instead of using a unit transistor array as coefficient transistors. A prototype second-order switched-current IIR filter array which consists of six second-order switched-current IIR filters has been fabricated with the standard 1.2 μm CMOS process technology. Hard wiring technique is used for programming the filters. The test results show that the characteristics of the filters satisfy the design requirements