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-mm² IC prototype has been fabricated in a 1.6-μm 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