Abstract: Some embodiments provide an oscillator that produces a signal at a desired frequency for use in a tuner. The oscillator comprises a filter and a frequency divider circuit comprising one or more frequency dividers in sequence, each frequency divider reducing a received frequency by a predetermined proportion. The frequency of the oscillator is controlled by a tuning code comprising a fine tuning code applied to the filter and a coarse tuning code applied to the frequency divider circuit. The filter is used to produce an initial frequency according to the fine tuning code and the frequency divider circuit divides down the initial frequency according to the coarse tuning code to produce a final frequency of the oscillator. Some embodiments provide an automated method and apparatus for tuning the oscillator to produce a signal at a desired frequency where the coarse tuning code is determined before the fine tuning code.

Abstract: A filter circuit topology for filtering a radio frequency input signal includes one or more inductor devices, such as, for example, discrete chip or air coils. The inductor devices are center tapped into a capacitor coupled to the ground. The center-tapped inductor configuration splits the output voltage across the inductor devices into two equal voltages of predetermined amplitude determined by the quality factor of the filter circuit. The filter circuit further includes an input capacitor to receive the RF input signal and an output capacitor coupled respectively to the inductor devices, the output capacitor having a variable capacitance, the inductor devices and the variable capacitor forming an inductive-capacitive (LC) filter capable of filtering the RF input signal and generating an output filtered signal for further transmission to a television tuner.