Methods and systems for filtering an input signal include receiving a first demodulated signal produced by multiplying a first generated signal with a received input signal, receiving a second demodulated signal produced by multiplying a second generated signal with the received input signal, and producing first and second filtered output signals by applying a transfer function to the first and second demodulated signals, wherein the transfer function comprises a first filtering coefficient, wherein the first filtering coefficient defines a matrix comprising one or more non-symmetrical terms. An application of the transfer function can compensate for one or more of an amplitude mismatch between the first and second generated signals, a phase mismatch between the first and second generated signals, and one or more frequency handling characteristics of channels used to produce the first and second demodulated signals.