TRANSMISSION MIXER WITH ELECTRIC CURRENT MODE INPUT

摘要

PROBLEM TO BE SOLVED: To perform an operation by a low voltage by converting an operation voltage to a differential current by a voltage/current conversion means and operating a differential mixer. SOLUTION: In the differential mixer of the transmitter of a GSM radio communication system, a stray balanced differential base band current INN is supplied to the differential amplifiers A and B of a high frequency part from a low frequency input voltage VIN by a voltage/current converter VIC and the VIC is operated as a current source for a high impedance at terminals TI1 and TI2. Thus, the voltage of the TI1 and TI2 is decided by the emitter voltage of the switching transistor of the differential amplifiers A and B regardless of the VIC and the common mode voltage of junctions J1 and J2 is related only to the input voltage of the common mode of high frequency radio signal input LO. A differential voltage between the TI1 and TI2 is decided by the input impedance of the emitter of the bipolar transistor of the amplifiers A and B and a modulation current INN and mixed with the high frequency input LO.