Various aspects of this disclosure describe the calibration of residual sideband energy in a receiver, for example estimating gain mismatch and phase mismatch in in-phase (I) and quadrature-phase channels (Q) of a receiver. An input to the receiver is supplied with an input signal generated to comprise a bandwidth including a plurality of frequencies, such as a linear frequency modulation signal. An output signal of the receiver is filtered by a filter programmed to be matched to the input signal, and estimates of gain error and phase error in I and Q channels of the receiver are determined from the filtered outputs.