A circuit includes a first biasing voltage source, a second biasing voltage source, a first resistor device coupled between the first biasing voltage source and a first terminal of the circuit, a second resistor device coupled between the second biasing voltage source and a second terminal of the circuit, a third resistor device coupled between the second biasing voltage source and a third terminal, a first capacitor coupled between the third terminal and ground, and an amplifier having an input coupled to the second terminal and an output coupled to a circuit output.

A musical instrument preamplifier includes a n-type JFET and a pnp current mirror connected to the drain side of the JFET. The pnp current mirror includes two pnp transistors. The current mirror is configured to control the current to independently set the operating point of the JFET and the output. An npn transistor is connected to one of the pnp transistors of the current mirror to form an inverted Sziklai pair. An auto-bias network is connected between the npn and pnp transistors that form the Sziklai pair.

An amplifier having one or more channels where each channel includes a two half bridges (a master and slave sub-channel). The sub-channels can be connected either in parallel or in a full-bridge configuration via internal switches that route signals to a pair of speaker jacks. One switch in the amplifier has a first position that selectively connects the outputs of the master and slave sub-channel to the same input of the speaker load so that the two sub-channels will drive the speaker load in parallel and a second position where the output of the slave sub-channel is connected to another input of the speaker load so that the master sub-channel and the slave sub-channel will drive the speaker load in a Full-bridge configuration. A second switch has a first position that connects a second input of the speaker load to ground or reference potential of the sub-channels when the speaker load is to be driven in parallel and a second position that is a No-connect position that is used when the speaker load is driven in the Full-bridge configuration and a ground potential is not to be connected to the speaker.

An amplifier having one or more channels where each channel includes a two half bridges (a master and slave sub-channel). The sub-channels can be connected either in parallel or in a full-bridge configuration via internal switches that route signals to a pair of speaker jacks. One switch in the amplifier has a first position that selectively connects the outputs of the master and slave sub-channel to the same input of the speaker load so that the two sub-channels will drive the speaker load in parallel and a second position where the output of the slave sub-channel is connected to another input of the speaker load so that the master sub-channel and the slave sub-channel will drive the speaker load in a Full-bridge configuration. A second switch has a first position that connects a second input of the speaker load to ground or reference potential of the sub-channels when the speaker load is to be driven in parallel and a second position that is a No-connect position that is used when the speaker load is driven in the Full-bridge configuration and a ground potential is not to be connected to the speaker.

A system for driving a transducer having a plurality of coils, the system comprising: a modulator for outputting a digital output signal representative of a received analogue input signal at a modulator output; a clock controlled delay element for applying a delay to the digital output signal to generate a first delayed signal at a delay element output; wherein the modulator output is couplable to a first coil of the plurality of the coils of the transducer and the delay element output is couplable to a second coil of the plurality of coils of the transducer.

The technology described in this document can be embodied in an apparatus that includes an amplifier that includes a first Zeta converter connected to a power supply and a load. The amplifier also includes a second Zeta converter connected to the power supply and the load. The second Zeta converter is driven by a complementary duty cycle relative to the first Zeta converter. The amplifier also includes a controller to provide an audio signal to the first Zeta converter and the second Zeta converter for delivery to the load.

An amplification system with an output driver stage for providing an output signal to acoustic output transducers such as speakers or haptic output devices removes signal distortion caused by output stage non-linearities by pre-distorting an input signal. The system includes the output driver stage, an input stage for receiving the input signal, and a processing block that receives the input signal and provides an output signal to the output driver stage. The processing block includes a pre-distortion circuit that applies a pre-distortion function to the input signal to generate the output signal if a signal level of the input signal is greater than a threshold amplitude, and if the signal level is less than or equal to the threshold amplitude, generates the output signal from the input signal by bypassing the pre-distortion circuit.

The audio amplification system comprises a power supply (100) connected to a feedback circuit (107), which is connected to the amplifier output filter, so that the power supply voltage (100) dynamically adjusts to the amplifier output voltage. Connected to the power supply (100) and mosfets (102) is a capacitor (108) with the function of stabilizing the power supply voltage (100). The system also comprises a control circuit (106), in which the mosfets (102) are connected, which connect to the output filter through an inductor (103) and a capacitor (104). The amplifier output (101) involves a speaker (105).

Provided herein are apparatus and methods for a multi-stage signal-processing circuit. The signal-processing circuit can include multiple configurable stages that can be cascaded and configured to process an input signal. Control circuitry can be used to select an output of the configurable stages. Serial data can be recovered with good signal integrity using a signal monitor with the configurable stages by virtually placing the signal monitor on a buffered output node.

Provided herein are apparatus and methods for a multi-stage signal-processing circuit. The signal-processing circuit can include multiple configurable stages that can be cascaded and configured to process an input signal. Control circuitry can be used to select an output of the configurable stages. Serial data can be recovered with good signal integrity using a signal monitor with the configurable stages by virtually placing the signal monitor on a buffered output node.