Configurable amplifier systems are described in which the power supply rail of a linear amplifier, e.g., a class A amplifier, is modulated by a switching amplifier, e.g., a class D amplifier, that may also be configured to operate independently of the linear amplifier. Techniques are also described by which the standing current of the output stage of a linear amplifier is modulated based on the input signal to the linear amplifier or based on modulation of the power supply rail of the linear amplifier.

An exemplary embodiment of the invention relates to an electrical amplifier comprising a differential preamplifier having a first output port and a second output port; and a downstream amplifier stage having a first output unit and a second output unit; wherein the first output unit is connected to the first output port of the differential preamplifier and the second output unit is connected to the second output port of the differential preamplifier; and wherein a negative impedance converter is electrically located in at least one of said differential preamplifier and said downstream amplifier stage.

An electrical system includes a power supply and an electrical circuit coupled to the power supply and including an operational amplifier. The operational amplifier includes an input stage and a pre-driver stage coupled to the input stage, wherein the pre-driver stage includes a first input terminal, a second input terminal, and a voltage supply terminal. The operational amplifier also includes an output stage with bipolar transistors coupled to the pre-driver stage. The pre-driver stage is configured to: detect a voltage differential across the first and second input terminals of the pre-driver stage; and provide an adjustable bias current based on the voltage differential.

An inverter circuit arrangement that connects an IO-link master with a slave includes an AB class transistor circuit of which the currents are replicated by a current mirror to a terminal of the slave. A bias circuit provides bias voltages to the AB class transistors. A comparator forms a feedback between the master and slave terminals. The circuit provides for a bidirectional inversion to make a slave device IO-link compatible.

Configurable amplifier systems are described in which the power supply rail of a linear amplifier, e.g., a class A amplifier, is modulated by a switching amplifier, e.g., a class D amplifier, that may also be configured to operate independently of the linear amplifier. Techniques are also described by which the standing current of the output stage of a linear amplifier is modulated based on the input signal to the linear amplifier or based on modulation of the power supply rail of the linear amplifier.

An operational amplifier including an input stage coupled to an input terminal, an output stage coupled to an output terminal, and a gain node between the input stage and the output stage. A bias current source is couplable to the input stage to supply a bias current thereto and a current mirror circuit mirrors the bias current toward the gain node and the output stage. A switch circuit includes a switch activatable to bring the gain node to a pre-bias voltage and a switch coupled to the output stage and switchable between a first state and a second state in which the output stage is active and non-active, respectively. A further switch circuit is coupled to the output terminal and switchable between a first state and a second state in which the output stage is coupled to the output terminal and to a reference level, respectively.

Devices, systems and methods for clamping output voltages of op-amps while minimizing post-clamping recovery delays are described. A circuit, which controls transitions between two operating modes, may include a first comparator for comparing an output voltage with a clamping voltage and outputting a first mode signal, a second comparator for comparing an input voltage with a reference voltage and outputting a second mode signal. A first logic component may receive the mode signals, perform a logical operation, and output a logic signal. A duplex output, based on a value of the logic signal, may output a track signal and an inversely corresponding hold signal, such track and hold signals being used by an op-amp circuit to configure adjusting blocks used to control transients during mode transitions.

The invention relates to a signal amplifier circuit for amplifying a signal, in particular an audio amplifier circuit, includes at least one first amplifier transistor (Q1) and at least one second amplifier transistor (Q2), wherein the first amplifier transistor (Q1) and the second amplifier transistor (Q2) are connected to one another in a push-pull circuit and are fed by an amplifier voltage source (V+, V); and one or more bias diodes (D1, D2) thermally coupled in each case to an associated amplifier transistor (Q1, Q2), wherein the bias diodes (D1, D2) are arranged in a parallel connection with respect to the amplifying transistors (Q1, Q2) to reduce or avoid a crossover distortion, wherein the bias diodes (D1, D2) are fed at least partly by a voltage source (UA) which is independent of the amplifier voltage source (V+, V). The invention furthermore relates to a system and a voltage converter for providing an output-side DC voltage, including a first transformer (T1) and a second transformer (T2) connected to the first transformer (T1).

Devices, systems and methods for clamping output voltages of op-amps while minimizing post-clamping recovery delays are described. A circuit, which controls transitions between two operating modes, may include a first comparator for comparing an output voltage with a clamping voltage and outputting a first mode signal, a second comparator for comparing an input voltage with a reference voltage and outputting a second mode signal. A first logic component may receive the mode signals, perform a logical operation, and output a logic signal. A duplex output, based on a value of the logic signal, may output a track signal and an inversely corresponding hold signal, such track and hold signals being used by an op-amp circuit to configure adjusting blocks used to control transients during mode transitions.

Apparatus and associated methods relating to the amplification of an audio signal. In particular, such application is performed by using an audio to pulse train converter configured to convert an analog audio signal to a complementary train of pulses having a duty cycle indicative of the level of the analog audio signal. The audio to pulse train converter can be a class-D amplifier, a sigma-delta amplifier, self-oscillating amplifier, or any other audio amplifier that is configured to provide complementary pulse trains each having a duty cycle that is representative of the input audio signal. The complementary pulse trains are directed to a circlotron that is configured to provide an amplified version of the audio signal at two output nodes. The amplifier circuit may further include one or more low pass filters and/or output reference resistors. Two similar circuits can be configured together to provide stereo audio amplification.