Abstract: A method for tuning and aligning an electronically tuned FM broadcast receiver is described. The system described compensates for the mismatch of component values between the antenna and RF amplifier tuned circuits, and the IF offset between the local oscillator frequency and the center frequencies of the antenna and RF resonant circuits by developing independent tuning signals for the circuits. The system also provides temperature compensation, and can be aligned without mechanically adjusting inductors and/or capacitors in the tuned circuits.

Abstract: A radio apparatus with a phase locked loop is disclosed. The apparatus contains a phase detector with first and second inputs, where the first input receiving a reference frequency signal and the second input receives a controllable frequency signal that is controlled by a tuning voltage. Also included is, a loop filter for filtering the output of the phase detector, circuitry for decoding when a phase difference at the inputs of the phase detector exceeds a predetermined value, and a filter bypass circuit. This circuit bypasses operation of the loop filter when the difference at the inputs of the phase detector exceeds a predetermined value, allowing fast voltage changes of the tuning voltage, and providing a short lock time for the phase locked loop.