a radio - frequency front - end circuit includes a tunable filter , a negative transconductance circuit coupled with the tunable filter to produce a tuning oscillation signal , and a counter arranged to determine a frequency of the tuning oscillation signal . the rf front - end circuit also includes a control circuit arranged to shift the frequency of the tuning oscillation signal by adjusting the tunable filter until the frequency of the tuning oscillation signal falls within an acceptable frequency range corresponding to a desired channel frequency band .