Devices and methods for reducing noise in digitally controlled oscillators

Abstract

One feature pertains to a digitally controlled oscillator (DCO) that comprises a variable capacitor and noise reduction circuitry. The variable capacitor has a variable capacitance value that controls an output frequency of the DCO. The variable capacitance value is based on a first bank capacitance value provided by a first capacitor bank, a second bank capacitance value provided by a second capacitor bank, and an auxiliary bank capacitance value provided by an auxiliary capacitor bank. The noise reduction circuitry is adapted to adjust the variable capacitance value by adjusting the auxiliary bank capacitance value while maintaining at least one of the first bank capacitance value and/or the second bank capacitance value substantially unchanged. Prior to adjusting the variable capacitance value, the noise reduction circuitry may determine that a received input DCO control word transitions across a capacitor bank sensitive boundary.