Double-split-electrode transversal filter for telecommunication applications

A novel structure for on chip tap weight implementation in CCD transversal filters is described which employs two splits in the CCD sensing electrodes to improve on the performance of the conventional single-split weighting technique. This greatly reduces the capacitance associated with the sensing nodes and consequently reduces the common mode signal, gain sensitivity, coefficient error, and clock noise pickup. Experimental results are presented which verify this improved performance. The results achieved for a 3.4-kHz low-pass filter clocked at 32 kHz show a signal-to-noise ratio of 86 dB with harmonic distortion of less than 0.3 percent.