Patent ID: 7383034
Filing Date: 2008-06-03
Classification: H03D,H04B

Abstract:
1. A frequency conversion circuit performing modulation by mixing an input signal with a local signal, the frequency conversion circuit comprises: a first input terminal pair inputted with the input signal; a second input terminal pair inputted with the local signal; an output terminal pair outputted with an output signal; a first transistor whose base is electrically connected with one of the first input terminal pair; a second transistor whose base is electrically connected with the other of the first input terminal pair; third and fourth transistors whose emitters are electrically connected respectively with a collector of the first transistor; fifth and sixth transistors whose emitters are electrically connected respectively with a collector of the second transistor; a differential noise suppression circuit which is provided between the collector of the first transistor and the collector of the second transistor, includes at least one capacitor, which suppresses a differential noise component of a frequency twice as large as a local signal frequency without repeating charging or discharging the capacitor with at least the local signal frequency, wherein one of the second input terminal pair is electrically connected with the base of the third and the sixth transistors, the other of the second input terminal pair is electrically connected with the base of the fourth and the fifth transistors, one of the output terminal pair is electrically connected with the collector of the third and the fifth transistors, and the other of the output terminal pair is electrically connected with the collector of the fourth and the sixth transistors.