C4 band-pass delay filter for continuous-time subband adaptive tapped-delay filter

This paper describes the implementation of delay element using C⁴ band-pass filter for subband analog tapped-delay adaptive filter, where implementation of larger group delay is required. Most analog delay elements have been implemented with low-pass and all-pass filters. While they can easily achieve constant group delay within pass band, maximum group delay is severely restricted by the corner frequency because group delay is inversely proportional to the corner frequency. We implemented a delay element with a capacitively-coupled current conveyor (C⁴) band-pass filter to produce larger group delay required for analog subband adaptive filter. Experimental results from circuits fabricated in 0.5 μm CMOS technology through MOSIS are also presented.