High-Efficiency Phased -Array Antenna Power Amplifier Modules

The power dissipation in amplifiers becomes a practical limit to the transmitter output power. One critical design goal for T/R modules, therefore, is maximization of the power-added efficiency (PAE) of the transmitter power amplifier. As more sophisticated modulation waveforms are introduced, however, power amplifiers in (or near) saturation introduce non-linear distortion of the signal in the form of amplitude and phase distortion and accompanying spectrum spreading and growth of unwanted side bands. In space-based systems, those limited assets available in space must be utilized to the maximum benefit, and it becomes necessary to contemplate the use of radar systems for multiple applications using multiples of carriers. As the prospect of using space-based assets for expanded applications with more than one carrier materializes, it becomes imperative to develop practical methods of reducing non-linear distortion and associated efficiency problems in power amplifiers. This proposal is addressed to those requirements, and novel circuit techniques such as pre-distortion circuits and the Doherty type amplifier circuits aimed at reduction of signal distortion and efficiency enhancement of power amplifiers are described.