Patent ID: 6922451
Filing Date: 2005-07-26
Classification: H04L

Abstract:
1. A digital circuit for shifting a frequency band of a signal vector to a predetermined frequency band, wherein the signal vector is determined by a pair of I (in-phase) and Q (quadrature) components on I-Q plane, comprising: a control data generator for generating control data from a frequency difference between the frequency band and the predetermined frequency band including a phase data generator for generating phase data from the frequency difference; a signal vector rotator for rotating the signal vector on the I-Q plane by an angle determined depending on the control data to produce an output signal vector in the predetermined frequency band; an analog-to-digital converter for converting a received analog signal vector to the signal vector according to a predetermined sampling clock, wherein the control data generator comprises; the phase data generator for generating the phase data from the frequency difference in synchronization with the predetermined sampling clock; and a converter for converting the phase data to the control data consisting of a plurality of control bits, and wherein the signal vector rotator comprises; a plurality of partial rotators which are connected in series in descending order of a rotation angle, wherein each of the partial rotators receives a different bit of the control bits of the control data and rotates an output of a previous stage by a predetermined angle depending on a corresponding control bit received from the converter.