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 (~ 10) and tunes its quality factor 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 0.25mum CMOS process and simulation results are presented