Rca Inc.

James C Whartenby

Mahesh Kumar

Richard N Brown

Srinivas T Rao

Raymond J Menna

A predistortion circuit for use with a solid state power amplifier or traveling wave tube amplifier which exhibits phase and amplitude nonlinearities. The predistortion circuit, which produces gain and phase distortion complementary to that of the associated power amplifier, comprises a hybrid circuit for splitting the input signal into two output signals at respective output terminals, the signals having a relative phase difference of 90.degree., a pair of dual gate FETs or other active nonlinear devices each connected to a different one of the two output terminals and a combiner for combining in-phase the outputs of the nonlinear devices. Bias on the nonlinear devices is adjusted to effect, in the predistortion circuit, nonlinearities complementary to those of the power amplifier.

Predistortion circuit

A predistortion circuit for a microwave power amplifier which exhibits phase and amplitude nonlinearities and has a small signal gain equal to a. The phase distortion circuit includes a 180.degree. coupler, a first coupler for coupling a given fraction of the input power to the 180.degree. coupler and a second coupler for coupling the given fraction of the power output from the amplifier, reduced by a, to the 180.degree. coupler. The 180.degree. coupler has a difference output port at which a signal appears which corresponds substantially to the difference in phase between the two signals input to the 180.degree. coupler and has a sum port at which a signal appears which corresponds substantially to the sum in amplitude between the two signals input thereto. A phase change circuit and attenuator are coupled between the first coupler and input to the power amplifier. Signals related to the signals produced at the difference port and sum port of the 180.degree. coupler are utilized to control the amount of phase change in the phase change circuit and the amount of attenuation in the attenuator circuit to thereby reduce the phase and amplitude nonlinearities of the signal produced by the power amplifier.

Predistortion circuit with feedback

A method is provided for fabricating a via connector from a first surface of a semiconductor wafer to an opposite second surface of the wafer. The first step consists of forming an adherent metal layer on the first surface on the semiconductor wafer. If the first surface of the semiconductor wafer has electronic components formed thereon, the metal layer is applied over the electronic components and preferably a protective layer of material is formed over the metal layer. Via holes are then laser drilled at predetermined locations through the metal layer and then through the semiconductor wafer. Thereafter a photoresist layer is applied over the first surface and exposed and developed to provide passage holes in the photoresist which are in alignment with the laser drilled apertures. The metal layer is then connected in the cathode position of the electroforming apparatus and via connectors are thereafter electroformed in the via holes.

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Trenton, NJ, United States of America

James C Whartenby