Capacitively-coupled current conveyer second-order section for continuous-time bandpass filtering and cochlea modeling

The capacitively-coupled current conveyer second-order section (C⁴ SOS) is a continuous-time bandpass filter with electronically tunable corner frequencies and ±40 dB/decade or greater roll offs. The corner frequencies can be set independently of each other, and the bandwidth can therefore be tuned at will. Each corner can have its own Q peak or, if the corners are brought close together, a very tight bandwidth with a single Q peak develops. This leads to further isolation of any given frequency and is thus useful for signal processing applications. An array of these C⁴ SOSs with exponentially spaced center frequencies forms a good model of the human cochlea (inner ear) where signals are decomposed with filtering processes that have Q≈30.