Abstract: A high efficiency outphasing power amplifier is disclosed which provides a high-efficiency, high-linearity outphasing amplifier capable of amplifying complex, wideband, multi-tone signals. Systems herein may amplify at least 256 symbol QAM signals with negligible distortion, while achieving high direct current-to-radio frequency efficiency sustainable at virtually all power levels. Embodiments of the outphasing amplifier employ a bridge output network formed from two complementary Class-D amplifiers to switch a dc supply voltage across the load. In embodiments, the phase of both halves of the bridge is varied from zero to +/?90 or zero to 180 degrees to split the workload, to correct for phase error within the bridge network and to control output power. Because the current through the load and thus through the two halves of the amplifier vary directly with output level, the efficiency remains high even when power output is low.

Abstract: A magnitude of radio frequency voltage and current, input into a load from a radio frequency power source, are measured at a single point along a transmission line. Phase difference between voltage and current is also measured. These measurements are used to compute VSWR and forward input power. The computed measurements may be compared against predetermined VSWR limits, and operation of the radio frequency power source can be adjusted to prevent damage to the detection apparatus or load.

Abstract: An apparatus and method of accomplishing over-voltage protection for variable power levels and frequency applications including the microwave range. Clamping means are provided that instantaneously absorb over-voltage conditions for a brief period while simultaneously providing feedback control of a driver signal to reduce the source of the over-voltage condition.

Abstract: An RF voltage/current sensor apparatus comprising a plurality of transmission lines coupled through resistive means to voltage sense circuitry. The voltage sense circuitry utilizes transistor technology thereby reducing the use of switching relays, transformers and diodes thereby providing an apparatus operational over a frequency range from approximately two megahertz to two gigahertz.

Abstract: A wideband high efficiency amplification system for amplifying radio frequency signals to high power levels. The system includes components adapted for generating an RF carrier signal having a multi-level waveform which may be characterized as a "modified square wave" including one or more intermediate voltage levels. This RF carrier waveform allows the power of the signal to be amplified with high efficiency beyond the efficiency levels which can ordinarily be achieved with conventional wideband class D amplifiers. The preferred embodiment of the invention describes an amplification system generating and using a three level waveform although waveforms having more than three levels may also be used.

Abstract: Intermodulation distortion in RF FET amplifiers operating in the Class AB mode is reduced without limiting the bandwidth by providing transformer coupled outputs from both the source and drain circuits. The negative feedback provided by the transformer in the source circuit reduces distortion but does not limit bandwidth in the manner of the reactive network normally used for correct phasing in circuits employing drain to gate feedback. Using this technique, the distortion components are typically 40-45 dB below the desired signal when a two-tone test is used, which exceeds the typically available level of 30 dB in prior art circuits.