A power amplifier is provided. The power amplifier may include a power transistor configured to amplify an input Radio Frequency (RF) signal and output the amplified signal, an overvoltage protection circuit configured to detect the magnitude of the input RF signal, and detect the magnitude of an output RF signal of the power transistor, and generate an overvoltage output signal based on the magnitude of the input RF signal and the magnitude of the output RF signal, and a bias circuit configured to generate a bias current to bias the power transistor, and adjust the bias current based on the overvoltage output signal.

In a system, apparatus and method for achieving scanning safety for a magnetic resonance conditionally safe implant, an FPO processor converts an RF power signal received from an RF power sensor of an MR scanner into an RF power parameter, and converts a gradient power signal received from an MR gradient power sensor of the MR scanner into a gradient power parameter. Upon detecting that the RF power parameter exceeds an RF power limit value or/and the gradient power parameter exceeds a gradient power limit value, the FPO processor sends a shutdown signal, to shut down an RF power amplifier or/and a gradient power amplifier in the MR scanner. The MR scanner is thereby enabled to realize the FPO mode, without altering MR scanner software, and the workload is small and easy to carry out.

A device includes a power control analog subsystem of a universal serial bus-power delivery (USB-PD) compatible power supply device. The power control analog subsystem includes a programmable current sensing circuit and a current sense resistor coupled to the power control analog subsystem. The power control analog subsystem is configured to concurrently compare a current flow through the current sense resistor with at least three different reference values, e.g., compare a sensed voltage with at least three different reference voltages.

Technology for a repeater is disclosed. The repeater can include a power amplifier and a controller. The controller can determine whether a load is connected to the repeater. The controller can protect the power amplifier when the load is not connected to the repeater by disabling the power amplifier. The controller can unprotect the power amplifier when the load is connected to the repeater by enabling the power amplifier.

Certain aspects of the present disclosure provide an amplifier for signal amplification. Certain aspects further describe methods and apparatus for applying overload protection for such amplifier. For example, one method generally includes detecting an overload condition of an amplifier based on a signal at a node of the amplifier, and controlling a parameter of an input signal of the amplifier such that the parameter of the input signal is maintained below a threshold based on the detection of the overload condition. The parameter of the input signal may include, for example, a voltage level or a duty cycle of the input signal.

Radio Frequency (RF) amplifiers with voltage limiting using non-linear feedback are presented herein. According to one aspect, an RF amplifier comprises an amplifier circuit having an input terminal and an output terminal and a non-linear feedback circuit having an input terminal and an output terminal. The input terminal of the non-linear feedback circuit is connected to the output terminal of the amplifier circuit and the output terminal of the non-linear feedback circuit is connected to the amplifier circuit to reduce the gain of the amplifier circuit when an RF voltage swing present at the input terminal of the non-linear feedback circuit exceeds a predefined threshold. In one embodiment, the output terminal of the non-linear feedback circuit is connected to the input terminal of the amplifier circuit. In another embodiment, the output terminal of the non-linear feedback circuit is connected to a bias circuit of the amplifier circuit.

Aspects of this disclosure relate to an impedance transformation circuit and overload protection for a low noise amplifier. A low noise amplifier can include a first inductor, an amplification circuit configured to amplify a radio frequency signal, and a second inductor magnetically coupled to the first inductor to provide negative feedback to linearize the low noise amplifier. A switch can be coupled to the amplification circuit of the low noise amplifier. An overload protection circuit can adjust an impedance of the switch based on a signal level associated with the radio frequency signal to provide overload protection for the low noise amplifier.

Components of a power amplifier controller may support lower voltages than the power amplifier itself. As a result, a surge protection circuit that prevents a power amplifier from being damaged due to a power surge may not effectively protect the power amplifier controller. Embodiments disclosed herein present an overvoltage protection circuit that prevents a charge-pump from providing a voltage to a power amplifier controller during a detected surge event. By separately detecting and preventing a voltage from being provided to the power amplifier controller during a surge event, the power amplifier controller can be protected regardless of whether the surge event results in a voltage that may damage the power amplifier. Further, embodiments of the overvoltage protection circuit can prevent a surge voltage from being provided to a power amplifier operating in 2G mode.

Components of a power amplifier controller may support lower voltages than the power amplifier itself. As a result, a surge protection circuit that prevents a power amplifier from being damaged due to a power surge may not effectively protect the power amplifier controller. Embodiments disclosed herein present an overvoltage protection circuit that prevents a charge-pump from providing a voltage to a power amplifier controller during a detected surge event. By separately detecting and preventing a voltage from being provided to the power amplifier controller during a surge event, the power amplifier controller can be protected regardless of whether the surge event results in a voltage that may damage the power amplifier. Further, embodiments of the overvoltage protection circuit can prevent a surge voltage from being provided to a power amplifier operating in 2G mode.

A phased array antenna system having a plurality of antenna elements arranged into an array is disclosed. Each of a plurality of amplifier circuitries has an output terminal coupled to a corresponding one of the plurality of antenna elements and includes a power amplifier having a control terminal coupled to an input terminal. The power amplifier has a first current terminal coupled to the output terminal and a second current terminal coupled to a fixed voltage node. Further included in each of the plurality of amplifier circuitries is a current limiter having a bias terminal coupled to the control terminal of the power amplifier to adjust a bias point of the power amplifier to limit current flowing through the first current terminal and the second current terminal to within a predetermined current range. Some embodiments also include a voltage limiter to limit voltage amplitude at the output terminal.