A power amplifier includes an over-current protection loop and/or an over-voltage protection loop to assist in preventing operation outside a safe operation zone. In a further exemplary aspect, triggering of the over-current protection loop adjusts a threshold voltage for the over-voltage protection loop. In further exemplary aspects, the over-current protection loop may adjust not only a bias regulator, but also provide an auxiliary control signal that further limits signals reaching the power amplifier. In still further exemplary aspects, the over-voltage protection loop may operate independently of the over-current protection current loop or the over-voltage protection loop contribute to an over-current protection signal.

Techniques are provided to more accurately determine reflected power, reflection coefficient, and/or voltage standing wave to permit prompt protection of components such as power amplifiers and notify communication system operators. This is accomplished by more accurately determining an amplitude and phase of an output reflected signal at an output port of a bidirectional coupler as a function of the following: an amplitude and a phase of a coupled forward signal coupled into a forward coupled port of the bidirectional coupler; an amplitude and a phase of a coupled reverse signal coupled into a reverse coupled port of the bidirectional coupler; an electrical transmission parameter from an input port of the bidirectional coupler to the forward coupled port; an electrical transmission parameter from the input port to the reverse coupled port; and an electrical transmission parameter from an output port of the bidirectional coupler to the reverse coupled port.

In certain aspects, a method is provided for measuring power using a resistive element coupled between a power amplifier and an antenna. The method includes squaring a voltage from a first terminal of the resistive element to obtain a first signal, squaring a voltage from a second terminal of the resistive element to obtain a second signal, and generating a measurement signal based on a difference between the first signal and the second signal. In some implementations, the resistive element is implemented with a power switch.

Disclosed is a system for monitoring the peak power of a telecommunication signal to be transmitted for RF power amplification of the telecommunication signal to be transmitted, including a digital processing device, a digital to RF converter and a dc-dc converter, wherein the output of the dc-dc converter can take a discrete voltage value from N discrete voltage values, N being an integer equal to or greater than 2, the digital processing device including a processing path including an envelope tracking control logic adapted to create a continuous envelope tracking control signal. The processing path further includes logic for driving the dc-dc converter including a peak value calculating device and a power supply voltage selecting device.

A directional coupler disclosed herein may include a main line provided on a substrate, the main line having a first end connected to an input port and a second end connected to an output port. The coupler may include a coupled line disposed on the substrate, the coupled line having a first end connected to a coupled port and a second end to an isolated port. The main line is electrically isolated from the coupled line. The coupled line includes multiple turns forming a winding, and a portion of the winding overlaps with the main line. The coupled line forms a plurality of windings inductively coupled with the main line. The main line and the coupled line are routed to propagate electric signals on both lines in a same direction, and enhance inductive coupling by mutual inductance.

A method includes determining one or more characteristics of a system that uses a power amplifier. The method also includes determining, based on the one or more determined characteristics, a switching speed and a supply voltage for the power amplifier. The method further includes modulating a power supply of the power amplifier according to the determined switching speed and supply voltage.

A low noise amplifying system with adjustable gain. The low noise amplifier includes a plurality of gain stages, including a first stage and a last stage each having fixed gain, and an intermediate stage having adjustable gain. The intermediate stage is an inverting gain stage that includes a field effect transistor connected from the output to the input, to provide negative feedback, reducing the gain as a control voltage (applied to the gate of the field effect transistor) is adjusted to decrease the channel resistance of the field effect transistor. A control circuit measures the input and output signal power of the amplifying system and adjusts the gain of one or more intermediate stages to trade off linearity against noise figure.

A method for predistorting an input signal of an amplifier device comprises evaluating a selection criterion for a computational model of the amplifier device. The computational model provides an output signal of the amplifier device for the input signal of the amplifier device. Further, the method comprises selecting between a first computational model of the amplifier device and a second computational model of the amplifier device based on the evaluated selection criterion. Additionally, the method comprises predistorting the input signal of the amplifier device using the selected computational model.

A digital microwave radio system includes a splitter that splits a common baseband input into two baseband outputs, first and second transmitters, each transmitter electrically connected to a baseband output of the splitter via a mixer, a common local oscillator electrically connected to the mixer of the first transmitter and the mixer of the second transmitter via an adjustable phase shifter, respectively, and a combiner. The common local oscillator is configured to up-convert each baseband output into a radio-frequency signal using a corresponding mixer. The combiner combines the two radio-frequency signals into a 0-degree phase-shift output and a 180-degree phase-shift output, respectively. A phase error control loop adjusts the phase shifter to minimize the 180-degree phase-shift radio-frequency output. A combiner gain control loop adjusts the output power level of the two transmitters in accordance with an actual power detector reading at the 0-degree phase-shift radio-frequency output.

A self-setting power supply monitors a supply current drawn by a power amplifier and sets a supply voltage based on the supply current to achieve efficient power operation. In order to maintain operation of the power amplifier above minimum operating conditions, the self-setting power supply sets the supply voltage to the minimum operating voltage when the supply current drops below a threshold bias current. When the supply current is above the threshold bias current, the self-setting power supply adjusts the supply voltage approximately proportionally to the supply current to maintain approximately constant gain of the power amplifier.