US Patent 7739069 Test prepared RF integrated circuit

In an example embodiment, an integrated circuit comprises a mixer circuit and a local oscillator circuit. During testing a frequency divider circuit in the integrated circuit divides a local oscillator signal to a frequency below a normal operating range of the local oscillator. The integrated circuit applies the divided local oscillator signal to the mixer circuit instead of the local oscillator signal during testing. Signal properties of a signal derived from the mixer circuit are measured while the divided local oscillator signal is applied to the mixer circuit.