An approach to programmable CTD filters using coefficients 0, + 1, and -1

A delta modulation-like sampled analog filter structure for realizing low-pass filters is described. The filter uses only the coefficients 0, + 1 , and -1 and can be fabricated as a programmable CCD filter. Interpolation and decimation are employed to increase the accuracy of the delta modulation. It is shown that with this scheme a given response can be realized arbitrarily closely. Examples are included.