Devices and methods for reducing noise in digitally controlled oscillators

摘要

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.

主权项

1. A digitally controlled oscillator (DCO), comprising:
a variable capacitor having a variable capacitance value that controls, in part, an output frequency of the DCO, the variable capacitance value 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; and noise reduction circuitry coupled to the variable capacitor, the noise reduction circuitry 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, wherein the noise reduction circuitry is further adapted to receive an input DCO control word and determine, prior to adjusting the variable capacitance value, that the received input DCO control word has transitioned between two boundary-sensitive control words at least one of a predetermined number of times or for a predetermined amount of time.