Patent ID: 8300744
Filing Date: 2012-10-30
Classification: H03D,H04B,H04L

Abstract:
1. An apparatus for rejecting image signals in a receiver of a direct conversion structure, the apparatus comprising: a signal mismatch compensation unit configured to detect gain error and phase error between an In-phase (I) signal and a Quadrature (Q) signal received through the receiver, to reject image signals existing in the I and Q signals, and to output a result, wherein the signal mismatch compensation unit detects the gain error and the phase error using an adaptive step method of reducing the step size of the gain error and the phase error step by step whenever the gain error and the phase error are converged, wherein the apparatus further comprises an offset compensation unit configured to reject DC offset signals from the I and Q signals received through the receiver and to output results to the signal mismatch compensation unit, wherein the offset compensation unit comprises two average units for estimating offset signals by taking a certain number of samples for the received I and Q signals; and two subtractors for subtracting the offset signals, estimated by the two the average units, from the respective I and Q signals and outputting I and Q signals from which the DC offset signals have been rejected, wherein the signal mismatch compensation unit comprises an image rejecter configured to reject image signals existing in the I and Q signals, received from the offset compensation unit, and to output I″ and Q″ signals; and an error detector configured to detect the gain error and the phase error between the I″ and Q″ signals, received from the image rejecter, based on a specific step, and to output the detected gain error and the detected phase error to the image rejecter, wherein the error detector decreases a step size whenever the gain error and the phase error are converged, and wherein the error detector comprises a gain error estimator configured to receive the I″ and Q″ signals from the image rejecter and to output a sign value of (I″)