Patent ID: 7983644

Claim:
In a circuit having a mixer with a radio frequency (RF) port and a bandpass filter having an input coupled to an output port of the mixer, the mixer responsive to a local oscillator (LO) signal coupled an LO port of the mixer, a method of compensating for passband variation of the bandpass filter, comprising: disabling the RF port; injecting the local oscillator signal into the LO port; leaking the local oscillator signal from the LO port to the bandpass filter input via the output port; determining an actual passband of the bandpass filter responsive to the LO signal; enabling the RF port; after the determining step, mixing an RF input signal, having a plurality of channels, with the LO signal to generate a mixer output signal; and adjusting a frequency of the LO signal based upon a selected channel of the plurality of channels and based upon the actual passband.