A calibration technique to compensate for the phase error between the in-phase and quadrature sampling clocks controlling the quadrature bandpass sampling delta-sigma analog-to-digital demodulator (QBS-ADD) is provided. A low-frequency test tone is injected, up-converted to the RF frequency, and added to an input of the QBS-ADD. The test tone is demodulated by the QBS-ADD into an in-phase signal and a quadrature signal. The in-phase and quadrature signals are filtered and multiplied together to generate a phase error signal, which is subsequently integrated to generate a phase shift control signal being used to correct the phase error between the in-phase and quadrature sampling clocks.