PROGRAMMABLE CMOS SWITCHED-CAPACITOR BIQUAD USING QUASI-PASSIVE ALGORITHMIC DACS

This paper describes an electrically programmable switched-capacitor ( SC) biquad using quasi-passive algorithmic digital-to-analog converter s (DAC's), Since only two equal-valued capacitors are needed for progr amming each capacitance value, the proposed technique offers compact, cost-effective programmability when compared to traditional programmin g techniques employing binary-weighted capacitor-arrays (C-arrays), A demonstration prototype chip realized in a 1.2 mu m CMOS double-metal double-poly technology, and which implements an 8 b programmable SC bi quad giving a wide range of lowpass, bandpass and highpass filtering f unctions, occupies an active area of only 0.38 mm(2).