Patent ID: 9647867
Date: 2017-05-09
CPC Classifications: H04B,H04L

Claim:
1. A direct down-conversion front end receiver, comprising an antenna for receiving an input radio frequency (RF) signal; first and second mixers connected to the antenna, for mixing the input RF signal with first and second orthogonal sinusoid signals for generating baseband quadrature and inphase signals respectively; first and second Q-channels connected to the first mixer, wherein the first Q-channel adds a baseband pseudo random binary sequence (PRBS) signal to the baseband quadrature signal, and filters the added baseband quadrature signal with a first quadrature filter response, to generate a first filtered quadrature signal, and wherein the second Q-channel subtracts the baseband PRBS signal from the baseband quadrature signal, and filters the subtracted baseband quadrature signal with a second quadrature filter response, to generate a second filtered quadrature signal; first and second I-channels connected to the second mixer, wherein the first I-channel adds the baseband PRBS signal to the baseband inphase signal, and filters the added baseband inphase signal with a first inphase filter response, to generate a first filtered inphase signal, and the second I-channel subtracts the baseband PRBS signal from the baseband inphase signal, and filters the subtracted baseband inphase signal with a second inphase filter response, to generate a second filtered inphase signal; Q-path and I-path PRBS cancellation blocks, wherein the Q-path PRBS cancellation block cancels corresponding PRBS component from a sum of the first and the second filtered quadrature signals to generate a modified quadrature signal, and wherein the I-path PRBS cancellation block cancels corresponding PRBS component from a sum of the first and the second filtered inphase signals to generate a modified inphase signal; Q-path and I-path sum filter estimation blocks, wherein the Q-path sum filter estimation block estimates a quadrature sum filter response from a difference of the first and the second filtered quadrature signals, and wherein the I-path sum filter estimation block estimates an inphase sum filter response from a difference of the first and the second filtered inphase signals; an IQ mismatch compensation filter estimate and tracking block, connected to the Q-path and I-path sum filter estimation blocks, for estimating an IQ mismatch compensation filter response from the estimated quadrature and the inphase sum filter responses; and an IQ mismatch compensation filter, connected to the IQ mismatch compensation filter estimate and tracking block, for filtering the modified inphase signal with the IQ mismatch compensation filter response, to generate a filter compensated inphase signal.