A low distortion transconductance amplifier provides current to a grounded load using a virtual ground input stage, a pair of current mirrors, and a bias current source. The virtual ground input stage may include transistors arranged as a Darlington pair. The low distortion transconductance amplifier can function as a voltage-controlled AC current source that is operable at high frequencies.

A circuit has an input and a two-wire output. The circuit is designed for use with HTPE transducers and comprised of four stages. The first stage is a charge amplifier based on operational amplifier, the second stage is a 1-pole passive low-pass filter, the third stage is an active 2-pole low-pass filter based on two JFETs, and the fourth stage is an emitter follower comprising two bipolar junction transistors connected to each other in Darlington configuration.

A circuit has an input and a two-wire output. The circuit is designed for use with HTPE transducers and comprised of four stages. The first stage is a charge amplifier based on operational amplifier, the second stage is a 1-pole passive low-pass filter, the third stage is an active 2-pole low-pass filter based on two JFETs, and the fourth stage is an emitter follower comprising two bipolar junction transistors connected to each other in Darlington configuration.

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.

Aspects of a distributed Darlington pair amplifier are described. In one example, a distributed amplifier device includes a number of distributed amplifier cells. The distributed amplifier cells can each include an input coupled to an input line and an output coupled to an output line. The amplifier device also includes a radio frequency input coupled to the input line and a radio frequency output coupled to the output line. One or more of the distributed amplifier cells can include a Darlington transistor pair rather than a common source transistor. The Darlington transistor pair can have a smaller gate-source capacitance than the common source transistor. This results in the ability to omit a series capacitor used with the common source transistor, improving the noise figure and gain over a range of operating frequencies for the distributed Darlington pair amplifier.

A differential power amplifier having first and second amplifiers with first and second signal output terminals along with bias circuitry in communication with the first and second amplifiers is disclosed. The differential amplifier further includes a first output clamp coupled to the first signal output terminal and a bias control terminal of the bias circuitry, wherein the first output clamp is configured to limit voltage at the first signal output terminal to a first predetermined voltage magnitude and lower bias current to the first amplifier in response to an overvoltage at the first signal output terminal. A second output clamp is coupled to the second signal output terminal and is configured to limit voltage at the second signal output terminal to a second predetermined voltage magnitude.

A differential power amplifier having first and second amplifiers with first and second signal output terminals along with bias circuitry in communication with the first and second amplifiers is disclosed. The differential amplifier further includes a first output clamp coupled to the first signal output terminal and a bias control terminal of the bias circuitry, wherein the first output clamp is configured to limit voltage at the first signal output terminal to a first predetermined voltage magnitude and lower bias current to the first amplifier in response to an overvoltage at the first signal output terminal. A second output clamp is coupled to the second signal output terminal and is configured to limit voltage at the second signal output terminal to a second predetermined voltage magnitude.

An amplifier that amplifies a differential signal includes first and second input terminals for receiving two input signals; first and second diodes each including an anode and a cathode, the anodes being electrically connected to the first and second input terminals; first and second bias current sources being respectively electrically connected to the cathodes of the first and second diodes; an operational amplifier connected to the cathode of the first diode and the cathode of the second diode and configured to amplify a differential signal between signals generated at the cathodes of the first and second diodes; a capacitive element being electrically connected between an input and an output of the operational amplifier; and a differential amplifier provided between the operational amplifier and the first and second input terminals and configured to amplify the two input signals. The first and second bias current sources include a current mirror circuit.

An output circuit of an amplifier which does not change power consumption. Since the output circuit of the amplifier does not flow, to a power supply circuit, a current correlated to a signal, the output circuit is not affected by the power supply circuit. The output circuit of the amplifier is provided with: a three-terminal amplifying element having an input terminal, an output terminal, and a common terminal; and a constant current circuit which is connected to the common terminal, and which flows a substantially constant current to the three-terminal amplifying element. The output terminal is grounded, and amplified output is taken out between the output terminal, and a contact point between the common terminal and the constant current circuit. Thus, the consumption current of the output circuit of the amplifier is merely the current flowing in the constant current circuit.

An amplifier that amplifies a differential signal includes first and second input terminals for receiving two input signals; first and second diodes each including anode and cathode, the anodes being electrically connected to the first and second input terminals; first and second bias current sources being respectively electrically connected to the cathodes of the first and second diodes; an operational amplifier connected to the cathode of the first diode and the cathode of the second diode and configured to amplify a differential signal between signals generated at the cathodes of the first and second diodes; a capacitive element being electrically connected between an input and an output of the operational amplifier; and a differential amplifier provided between the operational amplifier and the first and second input terminals and configured to amplify the two input signals. The first and second bias current sources include a current mirror circuit.