Patent ID: 8588336

Claim:
A method for compensating an imbalance between an in-phase, I, signal path and a quadrature, Q, signal path of a quadrature receiver adapted to generate a real-valued uncompensated digital I component a(n) and a real-valued uncompensated digital Q component b(n), together forming an uncompensated complex digital signal x(n)=a(n)+jb(n), wherein j denotes an imaginary unit and n is a sequence index, the method comprising: generating a complex compensation signal by filtering one of a(n) and jb(n) with a compensation filter having a complex-valued impulse response; generating a first compensated complex digital signal as the sum of x(n) and the complex compensation signal; and adaptively generating filter parameters of the compensation filter; wherein adaptively generating filter parameters of the compensation filter involves, for each of a number of iterations, where each iteration is identified by an iteration index i: generating filter parameters for attaining an impulse response f (i) (n), wherein f (i) (n) is a default impulse response for the first iteration, wherein i=1, and f (i) (n) is based on f (i−1) (n) and Δ (i−1) (n) for i>1, and Δ (i−1) (n) is an estimated impulse-response error of a preceding iteration; generating the complex compensation signal, denoted e (i) (n), as e (i) (n)=f (i) (n) * w(n), wherein * denotes the convolution operator and w(n) denotes one of a(n) and jb(n); generating the first compensated complex digital signal denoted v (i) (n), as v (i) (n)=x(n)+e (i) (n); and generating filter parameters determining Δ (i) (n) by minimizing a cost function based on u (i) (n)=v (i) (n)+Δ (i) (n)*w(n).