Patent ID: 8476981

Claim:
An unbalanced/balanced conversion differential amplifier comprising: a signal input of an unbalanced type relative to a reference potential; a signal output of a balanced type; first and second bipolar transistors mounted in a common emitter configuration, emitters of the first and second bipolar transistors being linked by two feedback impedances in series; and a perfect current generator, wherein an impedance Z g at the terminals of the perfect current generator is connected between a common point of the two feedback impedances and the reference potential, the signal input is connected to a base of the first bipolar transistor, a base of the second bipolar transistor is linked to the reference potential to form, with the base of the first bipolar transistor, the unbalanced signal input, the balanced signal output is produced by collectors of the first and second bipolar transistors through an impedance matching stage of the signal output, and a correction feedback impedance Z corr is connected between the collector of the second bipolar transistor and the base of the first bipolar transistor to balance the currents of the collectors of the first and second bipolar transistors, the value of said correction feedback impedance Z corr being defined by: Z corr =2· Zg.