Thomson-lgt Laboratoire General Des Telecommunications

Thomson-csf

Jean Michel

Jean-Claude Combe

Herminio De Faria

The disclosure relates to the linear power amplification, in a single channel, of a composite signal formed by two independent signals. In a single channel formed by correction means followed by a linear preamplifier followed by a saturated amplifier, the filtering and symmetry effect produced, both in the correction means and in the saturated amplifier, is advantageously used to compensate for clipping of the composite signal due to the amplifier. This makes it possible to obtain an undistorted output signal whose amplitude exceeds the level of saturation of the saturated amplifier. The compensation makes it necessary for the transfer characteristic of the correction means to have a given slope between two points beyond which the saturation appears in the saturated amplifier and a slope that is substantially thrice the given slope on each side of these two points.

Power amplifier device for a composite signal

A high-frequency wideband power amplifier, of the type comprising an amplifier stage with at least two transistors mounted as a differential stage, coupled at input and at output to a matching circuit further comprises, in order to convey each bias voltage to the amplifier stage, at least one high-frequency transmission line section with a length close to a quarter of the wavelength of the carrier of the signal to be amplified, the impedance of which, brought in parallel on each transistor, is negligible with respect to the high frequencies and the series impedance of which is negligible in the baseband of the signal to be amplified; the line sections conveying the bias voltages to the input of each transistor are identical to one another in length and in impedance, and the same is the case for the line sections conveying the bias voltages to the output of each transistor.

High-frequency wide band amplifier having reduced impedance

Method and apparatus for measuring the linearity of a transmission

A class AB amplifier and its distortion corrector are provided for obtaining linear amplification, even for low input signal levels. For this, at low levels, the distortion corrector has a response Vs'=f(Ve') (with Ve' and Vs': input and output voltages of the corrector) whose representative curve has a concavity turned towards the increasing values of Vs' whereas, up to now, a prejudice born of an insufficiently precise study of class AB amplifiers led to an inverse curve for the response of the corrector.

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Trappes, France

Jean Michel