A CMOS continuous-time bandpass filter with peak-detection-based automatic tuning

Automatic passband centring of an integrated high-frequency continuous-time filter has been accomplished using peak detection. In the paper an analysis of each block of the novel tuning circuit is given and the performance is evaluated in the presence of random device mismatches. Experimental results are given for an automatically tuned sixth-order bandpass filter. The filter's centre frequency deviates from its target value by less than 2%, which agrees well with theoretical calculations. Experimental prototype results further indicate that the tuning circuit is insensitive to changes in reference-frequency amplitude, and it functions well when subjected to a wide range of DC offset at its input.