Semiconductor integrated circuit

A semiconductor integrated circuit comprising:

• a mixer circuit which includes a first MOS transistor whose source is connected to a first terminal receiving a first current signal formed by voltage-current converting a radio frequency signal, whose gate receives a first local oscillation signal via a first capacitance, and whose drain is connected to a second terminal which outputs a second current signal with the first local oscillation signal superimposed thereon, and a second MOS transistor whose source is connected to the first terminal, whose gate receives, via a second capacitance, a second local oscillation signal which is an inverted signal of the first local oscillation signal, and whose drain is connected to a third terminal which outputs a third current signal with the second local oscillation signal superimposed thereon;
• a third MOS transistor whose drain is connected to a first potential, and which has a conductivity type and a threshold value which are the same as those of the first MOS transistor and the second MOS transistor;
• a current source connected between the source of the third MOS transistor and a second potential;
• a voltage dividing circuit which is connected between the first potential and the second potential, and divides a voltage between the first potential and the second potential to output the divided voltage as a reference voltage;
• and
• a differential amplifier circuit whose in-phase input receives the reference voltage, whose anti-phase input receives the source potential of the third MOS transistor, and whose output is connected to the gate of the third MOS transistor,
• wherein the output voltage of the differential amplifier circuit is applied to the gate of the first MOS transistor via a first resistor, and to the gate of the second MOS transistor via a second resistor, and
• wherein DC voltages of the drain and the source of the first and second MOS transistors are controlled to be equal to the reference voltage.