An integrated CMOS switched-capacitor bandpass filter based on N-path and frequency-sampling principles
Daniel C. von Grünigen, R.P. Sigg, John Robert Schmid, G.S. Moschytz, Hans M. Melchior · IEEE Journal of Solid-State Circuits · 1983
A new combined switched-capacitor (SC) frequency-sampling N-path filter is presented, which allows the implementation of very narrow bandpass filters. The included frequency-sampling (FS) filter suppresses undesirable passbands of the SC N-path filter. The center frequency f/SUB m/ of the bandpass filter is identical to the circuit clock frequency f/SUB c/. Experimental results are presented for a CMOS SC frequency-sampling four-path filter with second-order filter cells, a center frequency of 1 kHz, and -3-dB passband bandwidth of 11.5 Hz.