On the analysis of switched continuous time filters

A study of the operation of switched continuous time filters (SCTF), defined as continuous time filters with elements that are alternatively switched on and off in the signal path, is conducted. A detailed calculation of the output of a SCTF in the frequency domain, which allows a fast but exact analysis of any SCTF in a general framework, is presented. Several applications of SCTFs are shown and examined using the developed theory, including a non-ideal Sample & Hold, the realization of fully integrated extremely large time constants, filter tuning by varying the duty-cycle of the switching. A detailed noise analysis for switched operated filters is also presented.