Stmicroelectronics S.a.

Fabien Pousset

Jean-Charles Grasset

Philippe Cathelin

Frédéric Rivoirard

A transconducting device includes at least one transistor having a control electrode for receiving an input signal whose frequency spectrum contains two different frequencies, an output electrode for delivering an output signal, and a third electrode. The transconducting device further includes a voltage source for delivering a DC reference voltage, and a feedback controller for feedback-controlling the voltage on the third electrode to the DC reference voltage using a negative feedback loop. The negative feedback loop includes resistive damping, connects the third electrode and the control electrode, and has an open-loop gain greater than unity at a frequency equal to the frequency separation between the two different frequencies.

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A circuit for converting a differential signal into a nondifferential signal comprising first and second inputs respectively receiving first and second components of a differential signal. The circuit comprises a single bipolar transistor having an emitter, a base and a collector. The transistor is biased so as to allow flowing of an emitter d.-c. bias current sufficient to allow a linear conversion of a differential RF signal, for example. Both components of the differential RF signal are respectively injected into the emitter and the base of the bipolar transistor so that a remarkably linear conversion is carried out by means of a very simple circuit. The circuit is particularly adapted to the realization of an integrated RF transmission chain.

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Herbeys, France

Fabien Pousset