A tuner comprises a local oscillator including a variable capacitance diode. The output signal of the local oscillator is frequency divided by a prescaler and the frequency divided output is applied to a phase locked loop. The phase locked loop is structured such that the phases of the output signal...http://www.google.de/patents/US4320530?utm_source=gb-gplus-sharePatent US4320530 - Channel selecting apparatus employing frequency synthesizer
