Pseudo-N-path cells for switched-current signal processing

Novel switched-current pseudo-N-path cells are proposed, which allow the transformation of a z-domain lowpass reference filter into a bandpass one. The cells, a forward Euler, backward Euler, and a bilinear integrator, perform the z→, -z² transformation, and avoid clock-feedthrough noise in the filter passband. Operation of the cells is based on the pseudo-N-path, circulating delay principle to circumvent the problem of mirror-frequency noise due to path mismatches. An example of a 6th order elliptic bandpass filter obtained by transforming a third order lowpass reference is given. Simulated results demonstrate the usefulness of the proposed cells in the design of narrowband bandpass filters