Anadigics, Inc.

Aharon Adar

Sheldon Xu

A power amplifier has a plurality of amplifier stages. One or more predistorters are each placed between amplifier stages within the power amplifier path. The predistorters set breakpoints in a predistortion curve and divide the predistortion curve into a plurality of segments. Each predistorter may be adjusted to change the slope of each segment. This adjustment forms a piecewise curve-fit to approximate the inverse of the amplifier transfer characteristic. The curve-fit can be made arbitrarily close to the amplifier transfer characteristic by the selection of a sufficient number of breakpoints and therefore a sufficient number of predistortion curve segments, leading to a satisfactory linearization of the power amplifier.

Power amplifier having curve-fitting predistorter

The present invention discloses a miniature high directivity multi-band coupled-line coupler for RF power amplifier module application. The coupler utilizes a three-coupled-line structure, with a first RF line designated coupled line for the GSM 900 MHZ band, a second RF line designated coupled line for the DCS/PCS 1800/1900 MHZ band, and a common coupled line. A first capacitor is connected between the center of the first line and the center of the common line and a second capacitor is connected between the center of the second line and the center of the common line. The coupler has a length considerably less than the length of a quarter wave length coupler while achieving directivity requirements for both GSM band and DCS/PCS band.

High directivity multi-band coupled-line coupler for RF power amplifier

A GaAs MMIC dual-band amplifier for wireless communications is disclosed for operation at either the 800 MHz or the 1900 MHz band and it provides desired gain and input and output impedance. Switching impedance networks are used at the input and output of the amplifier to provide matching input impedance and desired output impedance for operation in the two bands. Switching impedance networks are also used between any successive stages of the amplifier to provide proper interstage impedance. The dual band amplifier includes a bias control circuit which biases the amplifier to operate in A, B, AB or C mode. The amplifier can be used for the AMPS 800 or the GSM 900 operation or any other cellular operation such as the PCS 1900 and the it can be switched between the two operations by simply applying a proper control signal to the amplifier.

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Berkeley Heights, NJ, United States of America

Aharon Adar