A charge amplifier circuit is provided. The charge amplifier circuit is couplable to a transducer that generates an electrical charge that varies with an external stimulus. The charge amplifier circuit includes an amplification stage having an input node, couplable to the transducer, and an output node. The amplification stage biases the input node at a first direct current (DC) voltage. The charge amplifier circuit includes a feedback circuit, which includes a feedback capacitor, electrically coupled between the input and output nodes of the amplification stage. The feedback circuit includes a resistor electrically coupled to the input node, and a level-shifter circuit, electrically coupled between the resistor and the output node. The level-shifter circuit biases the output node at a second DC voltage and as a function of a difference between the second DC voltage and a reference voltage.

The amplifier includes an input circuit configured to convert an input signal into a current; an output circuit comprising at least one switching element for reducing a voltage change of an output end of the input circuit and configured to provide an output signal; and a biasing circuit connected to the at least one switching element to form a feedback loop for reducing the voltage change of the output end of the input circuit.

In an example, a system includes an amplifier having an output stage configured to provide an output voltage, where the output stage includes a p-channel transistor and an n-channel transistor. The system includes a sense transistor having a gate coupled to a gate of the p-channel transistor, where the sense transistor is configured to sense a current of the p-channel transistor and produce a sense current. The system includes a current mirror coupled to the sense transistor and configured to provide the sense current to a gate of a control transistor, the control transistor having a source coupled to the gate of the p-channel transistor. The system includes a reference current source coupled to the control transistor and configured to provide a reference current. The control transistor is configured to adjust a gate current provided to the p-channel transistor based on comparing the sense current to the reference current.

A charge amplifier circuit is provided. The charge amplifier circuit is couplable to a transducer that generates an electrical charge that varies with an external stimulus. The charge amplifier circuit includes an amplification stage having an input node, couplable to the transducer, and an output node. The amplification stage biases the input node at a first direct current (DC) voltage. The charge amplifier circuit includes a feedback circuit, which includes a feedback capacitor, electrically coupled between the input and output nodes of the amplification stage. The feedback circuit includes a resistor electrically coupled to the input node, and a level-shifter circuit, electrically coupled between the resistor and the output node. The level-shifter circuit biases the output node at a second DC voltage and as a function of a difference between the second DC voltage and a reference voltage.

In an embodiment, a class-AB amplifier includes: an output stage that includes a pair of half-bridges configured to be coupled to a load; and a current sensing circuit coupled to a first half-bridge of the pair of half-bridges. The current sensing circuit includes a resistive element and is configured to sense a load current flowing through the load by: mirroring a current flowing through a first transistor of the first half-bridge to generate a mirrored current, flowing the mirrored current through the resistive element, and sensing the load current based on a voltage of the resistive element.

In an embodiment, a class-AB amplifier includes: an output stage that includes a pair of half-bridges configured to be coupled to a load; and a current sensing circuit coupled to a first half-bridge of the pair of half-bridges. The current sensing circuit includes a resistive element and is configured to sense a load current flowing through the load by: mirroring a current flowing through a first transistor of the first half-bridge to generate a mirrored current, flowing the mirrored current through the resistive element, and sensing the load current based on a voltage of the resistive element.

A charge amplifier circuit is provided. The charge amplifier circuit is couplable to a transducer that generates an electrical charge that varies with an external stimulus. The charge amplifier circuit includes an amplification stage having an input node, couplable to the transducer, and an output node. The amplification stage biases the input node at a first direct current (DC) voltage. The charge amplifier circuit includes a feedback circuit, which includes a feedback capacitor, electrically coupled between the input and output nodes of the amplification stage. The feedback circuit includes a resistor electrically coupled to the input node, and a level-shifter circuit, electrically coupled between the resistor and the output node. The level-shifter circuit biases the output node at a second DC voltage and as a function of a difference between the second DC voltage and a reference voltage.

The amplifier includes an input circuit configured to convert an input signal into a current; an output circuit comprising at least one switching element for reducing a voltage change of an output end of the input circuit and configured to provide an output signal; and a biasing circuit connected to the at least one switching element to form a feedback loop for reducing the voltage change of the output end of the input circuit.

An amplifier operates to provide a high output impedance at an output through a push stage having a first transistor of a first transistor type and a pull stage having a second transistor of a second transistor type that is different from the first transistor type. The first transistor and the second transistor are coupled in a common-gate configuration. The first transistor and the second transistor are shorted together via a capacitor coupled to an input and share a common current path as a push-pull current-reusing common-gate low noise amplifier with a broadband input matching.

In an example, a system includes an amplifier having an output stage configured to provide an output voltage, where the output stage includes a p-channel transistor and an n-channel transistor. The system includes a sense transistor having a gate coupled to a gate of the p-channel transistor, where the sense transistor is configured to sense a current of the p-channel transistor and produce a sense current. The system includes a current mirror coupled to the sense transistor and configured to provide the sense current to a gate of a control transistor, the control transistor having a source coupled to the gate of the p-channel transistor. The system includes a reference current source coupled to the control transistor and configured to provide a reference current. The control transistor is configured to adjust a gate current provided to the p-channel transistor based on comparing the sense current to the reference current.