Patent ID: 7809349

Claim:
A radio frequency (RF) filter comprising: an RF impedance circuit having a first RF impedance adapted to receive an RF input signal, wherein the RF impedance circuit comprises an RF output; an intermediate frequency (IF) impedance circuit comprising an IF input having an IF input impedance, wherein a magnitude of the IF input impedance is greater than a magnitude of the first RF impedance at frequencies that are at least one of a group consisting of a second harmonic and a fourth harmonic of a local oscillator frequency; and an RF passive mixer comprising: an RF input having an RF input impedance, wherein the RF input is coupled to the RF output to provide a filtered RF signal; a local oscillator input adapted to receive a local oscillator signal having the local oscillator frequency; and an IF output coupled to the IF input, wherein the IF input impedance is presented to the IF output, and the IF input impedance is translated into the RF input impedance by mixing the local oscillator signal with the filtered RF signal, wherein the first RF impedance and the RF input impedance form an impedance divider to create the filtered RF signal based on the RF input signal.