Abstract: Circuitry for controlling the oscillation frequency of an oscillator by using a digitally tunable on-chip capacitor bank. The capacitor bank includes a plurality of on-chip capacitors, each of which is independently selectable by a control signal for providing a selectable amount of capacitance to the oscillator to control the oscillator's oscillation frequency.

Abstract: An oscillator circuit including an integrated circuit amplifier, an integrated circuit active resistance circuit to set the gain of the amplifier, a crystal resonator to set the frequency of the signal generated by the oscillator circuit, and a pair of capacitors respectively situated at the inputs and outputs of the amplifier to assist in the starting of the oscillation signal. The active resistance circuit is responsive to an input signal in order to set the gain of the amplifier slightly above unity gain in order to meet the criterion for oscillation, but not too much above unity gain where the oscillator would unduly consume too much power. Thus, the oscillator has inherent low power characteristics. The active resistance circuit allows the amplifier gain to be set by software or other electronic means.