US Patent 7269404 Radio-frequency receiving apparatus

The subject invention provides a radio-frequency receiving apparatus including a built-in test signal source for producing a radio-frequency test signal. This structure achieves cost reduction, as well as an increase of the yield, since an expensive test signal source is not required. Further, the built-in test signal source creates a test signal by using signals from a VCO and an oscillator, that are used for creating a local oscillation signal for frequency conversion. Thus, the test can be performed inside the integrated circuit with minimum increase of circuit scale.