Patent ID: 7847642
Filing Date: 2010-12-07
Classification: H03B,H03J,H03L

Abstract:
1. A frequency tuning circuit, comprising: a first connecting terminal and a second connecting terminal configured to connect therebetween to a reference element having a single resonant frequency; a controllable-capacitance arrangement configured to tune the resonant frequency of the reference element, the arrangement comprising one control terminal configured to receive a tuning word as a control signal and a plurality of charge storage devices selectively connected to the control terminal via the tuning word, wherein the controllable-capacitance arrangement is connected to and arranged between the second connecting terminal that is connected to the reference element and a ground terminal; a control input configured to receive a digital control word; a sigma-delta modulator coupled to the control input and comprising an output coupled to the control terminal of the controllable-capacitance arrangement; and an adder, configured to: wherein the sigma-delta modulator is configured to oversample a second control word element to produce the adjusted control word element, wherein the digital control word comprises the first control word element of a first partial length and the second control word element of a second partial length, and wherein an input of the sigma-delta modulator is coupled to the control input and receives the second control word element, and wherein the number of switchable charge storage devices in the arrangement is a one-to-one correspondence to the first partial length of the first control word element.