Amplifying circuit with adjustable amplification and transmitter system comprising such an amplifying circuit

摘要

The invention is directed to an amplifier circuit with adjustable gain which includes a plurality of parallel-connected differential amplifiers connected to a common cascode stage. An actuation unit is used to activate the differential amplifiers independently of one another on the basis of an applied control signal. The principle described makes it possible to dispense with inductances in the differential amplifier and hence to reduce unwanted crosstalk, while having a high linearity. Secondly, the amplifier's drawn current matches the respective output power which can be tapped off. Overall, the principle described is particularly suitable for use in UMTS mobile radios.