Real time phase error detection in quadrature demodulators

An apparatus for detecting a Q-demodulator's real-time phase and offset error includes an RF signal path configured to receive an RF signal from an RF component, a first chopper to chop the RF signal at a first frequency to generate a chopped RF signal, an LO signal path configured to receive an LO signal, a second chopper to chop the LO signal at a second frequency to generate a chopped LO signal, a summing mechanism to combine the chopped LO signal to the chopped RF signal into a combination signal. The apparatus further includes a Q-demodulator comprising a phase shifter configured to shift a phase of the combination signal and a phase of the LO signal, and a mixer configured to multiply the shifted combination signal by the shifted LO signal to generate a baseband signal, and at least two filters configured to extract different signals contained in the baseband signal for analysis.