Programmable switched-current wave analog filters

This paper presents a methodology to realize programmable switched-current filters. A universal wave filter structure is built based on a low-pass (LP) to band-pass (BP) frequency transformation in the z-domain that allows obtaining different filtering functions from a single low-pass reference filter without altering the global circuit topology. Two different parameters, modified by changing the gain of current mirrors, independently control the filter bandwidth and center frequency. A 2.88-mm/sup 2/ IC prototype has been fabricated in a 1.6-/spl mu/m CMOS digital technology that is capable of implementing three LP's (and their three complementary HP's) and nine BP's (and their nine complementary BR) Chebyschev filters. The realization of the 24 filtering functions requires less than 15% of additional area than that required to implement only one BP function. The chip operates from a 5-V supply, dissipates 0.83 mW/pole, and met the expected performance levels for all filter functions.<
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