Disclosed is an amplifier circuit for providing an output of at least 100 W, preferably of at least 200 W and most preferably of at least 250 W comprising a field effect transistor. A drain of the field effect transistor is connected with a protective feedback circuit. The protective feedback circuit is arranged to reduce an over-voltage energy at the drain of the field effect transistor if the voltage between the gate and a drain of the field effect transistor exceeds a feedback threshold voltage. Further disclosed is a radio frequency amplifier comprising an amplifier circuit, an electrical radio frequency generator comprising the radio frequency amplifier and a plasma processing system comprising an electrical radio frequency generator. Still further disclosed is a method of protecting a field effect transistor in an amplifier circuit.

An interface circuit comprises a signal path including a front-end charge amplifier coupling an input of the interface circuit to an output of the interface circuit, and a DC control loop separate from the signal path. In some implementations, the interface circuit is part of a MEMS sensor that includes a MEMS transducer having an output coupled to the input of the interface circuit. The interface circuit can, in some cases, allow faster settling of the circuit to its steady-state operating point.

An amplifier with two parallel coupled amplifier units with inverse characteristics and in particular to the parallel coupling of a sourcing limited amplifier unit and a sinking limited amplifier unit.

An amplifier circuit amplifies a radio-frequency signal. The amplifier circuit includes an amplifier, an input matching circuit connected to an input side of the amplifier and matches impedance, and a protection circuit connected to a node in a path within a path between an input matching circuit and the amplifier. The protection circuit includes a first diode connected between the node and a ground, and a second diode connected in parallel with the first diode and connected in a direction opposite to the first diode between the node and the ground. A threshold voltage of each of the first diode and the second diode is greater than a maximum voltage amplitude of the input signal at the node and is less than a difference between a withstand voltage of the amplifier and the bias voltage.

An amplification device includes an amplification circuit and a protection circuit. The amplification circuit includes a transistor having a first terminal for outputting an amplified radio frequency signal, a second terminal, and a control terminal coupled to the input terminal of the amplification circuit for receiving a radio frequency signal to be amplified. The protection circuit has a first terminal coupled to the output terminal or the input terminal of the amplification circuit, and a second terminal. The protection circuit includes a switch and a first voltage clamping unit. The switch unit is turned on or turned off according to a control signal. The first voltage clamping unit is coupled to the switch unit for clamping a voltage at the first terminal of the protection circuit within a predetermined region when the switch unit is turned on.

Various methods and circuital arrangements for protection of an RF amplifier are presented. According to one aspect, the RF amplifier is part of switchable RF paths that include at least one path with one or more attenuators that can be used during normal operation to define different modes of operation of the at least one path. An RF level detector monitors a level of an RF signal during operation of any one of the switchable RF paths and forces the RF signal through the at least one path with one or more attenuators while controlling the attenuators to provide an attenuation of the RF signal according to a desired level of protection at an input and/or output of the RF amplifier.

An overvoltage protection circuit includes an input terminal, an output terminal, a clamp transistor, and a selector circuit. The clamp transistor is configured to control current flow between the input terminal and the output terminal. The clamp transistor includes a first terminal coupled to the input terminal, a second terminal coupled to the output terminal. The selector circuit is configured to control a resistance of the clamp transistor based on a voltage at the input terminal. The selector circuit includes a first terminal coupled to the first terminal of the clamp transistor, a second terminal coupled to the second terminal of the clamp transistor, and a third terminal coupled to a third terminal of the clamp transistor.

A circuit element is formed on a substrate made of a compound semiconductor. A bonding pad is disposed on the circuit element so as to at least partially overlap the circuit element. The bonding pad includes a first metal film and a second metal film formed on the first metal film. A metal material of the second metal film has a higher Young's modulus than a metal material of the first metal film.

A power amplifier circuit includes a first amplifier that amplifies an input signal and outputs a first amplified signal, a second amplifier that is disposed subsequent to the first amplifier and that amplifies the first amplified signal and outputs a second amplified signal, and a clamp circuit that is disposed between ground and a signal line extending between the first amplifier and the second amplifier and that suppresses an amplitude of the first amplified signal.

An amplification system includes a first amplification module, a second amplification module, a third amplification module I, a fourth amplification module I, a first load, a third amplification module II, a fourth amplification module II and a second load. An output terminal of the first amplification module is connected to an input terminal of the second amplification module; output terminals of the second amplification module are connected to an input terminal of the third amplification module I and an input terminal of the third amplification module II. An output terminal of the third amplification module I is connected to an input terminal of the first load through the fourth amplification module I. An output terminal of the third amplification module II is connected to an input terminal of the second load through the fourth amplification module II.