A high-Q bandpass filter demonstrating charge domain technology

A new class of integrated circuits has been developed which utilizes charge domain concepts to realize analog/sampled data signal processing functions at high speeds. By splitting and summing minority carrier charge packets, both poles and zeroes of a transfer function can be implemented without any active gain elements. This charge domain concept combined with the small output capacitance of these devices should permit signal processing functions to be performed at speeds approaching that of simple CCD delay lines. A high-Q 8-pole bandpass filter was chosen to demonstrate these unique capabilities of Charge Domain Devices (CDD´s). With the center frequency at 1/4 of the clock frequency (Fc), the passband over 1% of Fcis flat to 1 dB. For a 2% Fcpassband the attenuation is 18 dB. The calculated frequency response continues to tail off to over 100 dB stopband attenuation at the Nyquist frequency.