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 current flow control device includes a plurality of semiconductor switches disposed between a power source and a load and that are connected in parallel with each other, and the current flow control device being configured to control the flow of current between the power source and the load by turning on and off the semiconductor switches. The plurality of semiconductor switches include a first and a second semiconductor switch. The current flow control device includes a driving circuit configured to apply, to the first semiconductor switch, a voltage that is higher than a voltage output from the power source, to turn on the first semiconductor switch, a switch control unit configured to turn on the second semiconductor switch, and a resistor that is connected in series with a terminal on the power source side of the second semiconductor switch, the resistor lowering a voltage applied to the terminal.

A power amplifier with clamp and feedback protection circuitry is disclosed. In one aspect, the power amplifier is initially protected by a fast-acting clamp circuit whose overall size is relatively limited. Subsequent operation allows a comparatively slowly acting feedback loop to dominate the protection of the power amplifier. By providing the two protection circuits, each optimized for a particular phase of protection, the overall size of associated protection circuitry may be diminished while still protecting the power amplifier from failure inducing conditions.

A power amplifier with clamp and feedback protection circuitry is disclosed. In one aspect, the power amplifier is initially protected by a fast-acting clamp circuit whose overall size is relatively limited. Subsequent operation allows a comparatively slowly acting feedback loop to dominate the protection of the power amplifier. By providing the two protection circuits, each optimized for a particular phase of protection, the overall size of associated protection circuitry may be diminished while still protecting the power amplifier from failure inducing conditions.

A power amplifier system is disclosed having a first stage amplifier that includes a first supply terminal, a first input, and a first output. A second stage amplifier has a second supply terminal, a second input, and a second output. A first stage bias circuitry has a bias output coupled to a bias input of the first stage amplifier and a bias control input. Absolute maximum ratings protection circuitry has a voltage monitoring input coupled to the second supply terminal and a bias control output coupled to the bias control input, wherein the absolute maximum ratings protection circuitry is configured to reduce the bias of the first stage amplifier through the bias control output based upon voltage monitored at the voltage monitoring input exceeding a predetermined voltage level. Additional absolute maximum ratings protection circuitry reduces the bias of the first stage amplifier if first stage amplifier supply voltage is excessive.

A power amplifier system is disclosed having a first stage amplifier that includes a first supply terminal, a first input, and a first output. A second stage amplifier has a second supply terminal, a second input, and a second output. A first stage bias circuitry has a bias output coupled to a bias input of the first stage amplifier and a bias control input. Absolute maximum ratings protection circuitry has a voltage monitoring input coupled to the second supply terminal and a bias control output coupled to the bias control input, wherein the absolute maximum ratings protection circuitry is configured to reduce the bias of the first stage amplifier through the bias control output based upon voltage monitored at the voltage monitoring input exceeding a predetermined voltage level. Additional absolute maximum ratings protection circuitry reduces the bias of the first stage amplifier if first stage amplifier supply voltage is excessive.

An apparatus includes a photodetector configured to generate an electrical current based on received illumination. The apparatus also includes a capacitor transimpedance amplifier (CTIA) unit cell having (i) an amplifier configured to receive the electrical current and a reference voltage, (ii) a feedback capacitor coupled in parallel across the amplifier, and (iii) a reset switch coupled in parallel across the feedback capacitor. The apparatus further includes an event detector configured to sense a high-energy event affecting the photodetector. In addition, the apparatus includes a switchable clamp coupled across inputs of the amplifier, where the event detector is configured to close the switchable clamp in response to sensing the high-energy event.

An apparatus includes an amplifier circuit and a protection circuit. The amplifier circuit may be configured to generate an output signal by amplifying an input signal received at an input port. The input signal may be a radio-frequency signal. The protection circuit may be configured to (i) generate a detection signal by detecting when a level of the input signal exceeds a corresponding threshold, where the level is a power level, a voltage level or both, (ii) route the input signal away from the input port of the amplifier circuit and disable the amplifier circuit both in response to the detection signal being continuously active at least a first time duration and (iii) route the input signal to the input port of the amplifier circuit and enable the amplifier circuit both in response to the detection signal being continuously inactive at least a second time duration.

A protection circuit comprises a first transistor, a comparator, a second transistor, and a third transistor. The first transistor has a gate connected to an input terminal and configured to pass a drain current based on a potential at the input terminal. The comparator has a non-inverting terminal to which a source of the first transistor is connected and an inverting terminal to which a reference voltage is applied. The second transistor has a gate to which an output of the comparator is applied, a source connected to a power supply voltage, and a drain connected to the input terminal. The third transistor has a gate to which a predetermined voltage is applied, a drain connected to the gate of the second transistor, and a source connected to the drain of the input transistor.

Provided is an input voltage endurance protection architecture applied to a high-voltage operational amplifier with high input amplitude and high linearity. The input voltage endurance protection architecture includes three parts: a main operational amplifier, an auxiliary operational amplifier and an input stage voltage endurance protection circuit. The main operational amplifier is a high-voltage general-purpose operational amplifier, the auxiliary operational amplifier is a single-stage differential amplifier, and the single-stage differential operational amplifier is connected to a degeneration resistor Rbias. In addition, the auxiliary operational amplifier has a same connection method as the main operational amplifier at a positive input terminal and a negative input terminal, and both the positive input terminal and the negative input terminal are protected by an input stage voltage endurance protection circuit and receive and process input signals simultaneously.