Stmicroelectronics S.a.

Jean-Charles Grasset

Philippe Cathelin

Frédéric Rivoirard

Christophe Pinatel

Bruno Pellat

Frederic Bossu

Kuno Lenz

Frédéric Bossu

Fabien Pousset

Sylvie Gellida

A radio frequency stage comprises an analog multiplier cell, and an analog current routing cell coupled thereto. The analog multiplier cell includes an input for receiving an input current having a DC component and a radio frequency dynamic component, and a controllable current source for delivering a DC control current. A current multiplication circuit generates an output current having a radio frequency dynamic component equal to a product of the dynamic component of the input current times a multiplier coefficient dependent on a ratio between a value proportional to that of the DC control current and a value of the DC component of the input current. An output delivers the output current. The analog current routing cell includes an input coupled to the output of the analog multiplier cell. A controllable voltage source delivers a control voltage and a routing circuit for routing a part of the input current to the output of the analog routing cell as a function of the value of the control voltage.

Controllable radio frequency stage with variable gain/attenuation, in particular incorporated into the transmission chain of a cellular mobile telephone, and corresponding control method

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.

Circuit for converting a differential signal into a non-differential signal, and RF transmitter comprising such a circuit

A radiofrequency amplifier device includes a transconductor stage having an input for receiving a radiofrequency signal, and a cascode stage connected to the output of the transconductor stage. The device also includes an auxiliary radiofrequency amplifier compensation stage connected as a negative-feedback loop between the output of the transconductor stage and the base or the gate of the cascode stage.

Radiofrequency amplifier device, in particular for cellular mobile telephone

A direct conversion type of frequency transposition device includes a transconductor block receiving the input signal and a current switching block connected to the output from the device. At least the common mode (I+I) is servocontrolled to static output currents from the frequency transposition device on a current proportional to a reference current (I) and independent of the static output currents from the transconductor block.

Process for control of standby currents in a direct conversion type of frequency transposition device, and corresponding device

Attenuation cell comprising first and second differential pairs of bipolar transistors. A gain control device applies a voltage VA&#x2212;VB between the bases of both differential pairs and comprises a set of three diodes in which a current IA, a current IB and the sum IA+IB of both preceding currents flow, respectively. The two diodes seeing current IB and IA+IB generate a voltage, respectively VB and VC, and the difference between these two voltages is used to generate a value Iz used in a control loop. A desired value Vct is transformed into information Ix, then into information Iy proportional to absolute temperature T, and an error amplifier uses information Iy&#x2212;Iz and generates currents IA and IB by minimizing this difference.

Attenuation cell with an attenuation factor control device

An amplifier including an input circuit tuned to the frequency to be amplified and receiving as an input the signal to be amplified, a first transistor connected in common base, the emitter of which is coupled to the input circuit and the collector of which provides the output signal of the amplifier, and a feedback circuit feeding back to the base of the transistor a fraction of the output voltage. The feedback circuit includes a capacitive bridge and a second transistor. The input circuit can be used in a first stage of the amplifier or of a mixer.

Linear pre-amplifier for radio-frequency power amplifier

A transconductance stage includes at least one principal bipolar transistor having a base linked to an input terminal, a collector linked to an output terminal, and an emitter linked to a supply terminal through a resistor. At least one bipolar compensation transistor is connected in parallel to the principal transistor and linked without going through the resistor to the supply terminal. The value Rof the resistance is chosen so that R*I&#x3e;V/2, where Vis the thermal voltage and Iis the quiescent current of the principal transistor.

Transconductance stage and device for communication by Hertzian channel equipped with such a stage

The operation of a bipolar transistor is controlled comprising by producing a first voltage that is a product of a static collector current of the bipolar transistor times an emitter resistance. The first voltage is then compared to a predetermined reference voltage to produce a control signal. Current is then injected a base of the bipolar transistor in response to the control signal. In a specific implementation, the first voltage, which is a product of the static collector current (Ic) of the bipolar transistor times its emitter resistance (RE) , is slaved to a predetermined reference voltage (Vref) whose value is substantially equal, to within a tolerance, to 13 mV at a temperature at or about 27&#xb0; C.

Process and device for controlling the operation of a bipolar transistor in class A

A biasing device includes closed-loop transconductance slaving circuit, able to slave the time average of the base/emitter or gate/source voltage of the amplifier transistor (Q ) to a reference voltage corresponding to a desired quiescent current for the transistor. Moreover, viewed from the base or gate of the amplifier transistor (Q ), the impedance of the base/emitter or gate/source circuit is small at low frequency, and large with respect to the impedance of the radio frequency source within the radio frequency range of the signal. The device can be incorporated in a mobile terminal, such as a cellular mobile phone.

Method and device for biasing a transistor of a radio frequency amplifier stage

A power amplifier includes an input terminal, and a gain control circuit connected to the input terminal. The gain control circuit includes a circuit for providing a control signal, and at least a first pair of transistors. Each transistor includes a control terminal, a first conduction terminal and a second conduction terminal. The control terminals are connected together for receiving the control signal for control thereof. The first conduction terminals are connected together and to the input terminal. The at least one first pair of transistors defines a voltage/current transconductor circuit for converting an input voltage into an input current, and defines a shunt circuit for shunting at least a portion of the input current.

Controlled-gain power amplifier device, in particular for radio-frequency circuits applied to cellular mobile telephony

The residual quantity of a local oscillator signal in the output signal from a frequency transposition device having a differential Gilbert type structure is reduced by biasing the transistors of the output stage of the differential transconductor block of the device. The biasing is performed by carrying out differential slaving of the conduction terminal of these transistors to a predetermined common mode current.

Frequency transposition device having low local oscillator signal leakage and corresponding leakage reduction process

A mixer including a stage for inputting a voltage signal to be shifted and a shift and output stage for providing frequency-shifted signals, a biasing network of the output stage including, between a high supply and a biasing node, a constant current source in parallel with an output element of a current mirror, an input element of which receives a bias order from the input stage.

Growing community of inventors

Moirans, France

Jean-Charles Grasset