Patent ID: 7493098

Claim:
A semiconductor integrated circuit, comprising: a first transistor through which a direct current and an alternate current corresponding to an input signal of a first frequency are passed; a second transistor, to an emitter or source of which an output current from a collector or drain of the first transistor is inputted, to a control terminal of which a signal of a second frequency is applied, and from a collector or drain of which a signal generated by combining the input signal of the first frequency and the signal of the second frequency is outputted; and a low-pass filter including a load resistor and a capacitive element and being connected to the collector or drain of the second transistor; wherein a current injection circuit for applying a part of the direct current passing through the first transistor without making the part of the direct current pass through the load resistor is provided, and wherein the load resistor and the capacitive element are formed on a semiconductor substrate where the first transistor and the second transistor are also formed.