Q locked loop to tune a high-Q high-frequency bandpass filter

A novel quality factor tuning scheme to tune a high-Q, high-frequency G(m)C bandpass filter is presented. The proposed Q tuning loop tunes the filter phase characteristics inside a phase locked loop system to tune its quality factor. Filter is used as a voltage controlled oscillator of the phase locked loop system. The proposed tuning scheme starts the 70MHz filter from a low-Q region (similar to 10) and tunes its quality factor to similar to 50. The mathematical analysis and the loop stability of the proposed scheme is presented and analyzed. The proposed Q locked loop is simulated in 0.25 mu m CMOS process and simulation results are presented.