Monolithic minimum phase CCD channel filter for a PCM codec employing overlapping-double-split-electrode technique

A monolithic CCD channel filter consisting of transmit-and-receive filters for a PCM codec was fabricated using a triple-layer polysilicon gate and NMOST process. This filter employed both a minimum phase design with a greatly reduced number of taps and newly developed overlapping-double-split-electrode (ODSE) structure in order to minimize chip area and eliminate excess capacitances at all of the sensing nodes. Improved filter performance, such as negligible degradation in frequency response, reduced power dissipation, a significantly small common mode signal, and consequently, much improved signal-to-noise ratio are discussed. Frequency responses, harmonic contents, and noise spectral densities are presented as experimental results. Signal-to-noise ratio was measured to be 84 dB with a total harmonic distortion of less than 0.4 percent.