A half bridge circuit is disclosed. The circuit includes low side and high side power switches selectively conductive according to one or more control signals. The circuit also includes a low side power switch driver, configured to control the conductivity state of the low side power switch, and a high side power switch driver, configured to control the conductivity state of the high side power switch. The circuit also includes a controller configured to generate the one or more control signals, a high side slew detect circuit configured to prevent the high side power switch driver from causing the high side power switch to be conductive while the voltage at the switch node is increasing, and a low side slew detect circuit configured to prevent the low side power switch driver from causing the low side power switch to be conductive while the voltage at the switch node is decreasing.

An impedance measurement circuit for determining a sense current of a guard-sense capacitive sensor operated in loading mode. The circuit includes a periodic signal voltage source for providing a periodic measurement voltage, a sense current measurement circuit, a differential amplifier that is configured to sense a complex voltage difference between the sense electrode and the guard electrode, a demodulator for obtaining, with reference to the periodic measurement voltage, an in-phase component and a quadrature component of the sensed complex voltage difference, and control loops for receiving the in-phase component and the quadrature component, respectively. An output signal of the first control loop and an output signal of the second control loop are usable to form a complex voltage that serves as a complex reference voltage for the sense current measurement circuit.

An impedance measurement circuit for determining a sense current of a guard-sense capacitive sensor operated in loading mode. The circuit includes a periodic signal voltage source for providing a periodic measurement voltage, a sense current measurement circuit, a differential amplifier that is configured to sense a complex voltage difference between the sense electrode and the guard electrode, a demodulator for obtaining, with reference to the periodic measurement voltage, an in-phase component and a quadrature component of the sensed complex voltage difference, and control loops for receiving the in-phase component and the quadrature component, respectively. An output signal of the first control loop and an output signal of the second control loop are usable to form a complex voltage that serves as a complex reference voltage for the sense current measurement circuit.

According to an aspect, an audio amplifier includes a first sigma-delta modulator configured to receive a digital audio signal and generate a first multi-level output signal based on the audio signal, and a second sigma-delta modulator configured to receive the first multi-level output signal from the first sigma-delta modulator and generate a second multi-level output signal. The second multi-level output signal has a number of levels less than a number of levels of the first multi-level output signal.

A circuit that outputs a current which is proportional to an input voltage includes input and output terminals, a comparator, first and second transistors, an inductor, a first resistor, and a differential amplifier. A first input terminal of the comparator is coupled to the input terminal of the circuit, and a second input terminal of the comparator is coupled to an output terminal of the comparator. The first and second transistors are coupled to the output terminal of the comparator. The inductor is coupled to the first and second transistors. The first resistor is coupled between the inductor and the output terminal of the circuit. The differential amplifier includes a first input terminal coupled to a first terminal of the first resistor, a second input terminal coupled to a second terminal to the first resistor, and an output terminal coupled to the first input terminal of the comparator.

An isolation amplifier includes an input circuit at high voltage potential with an input for a measurement signal to be transmitted, an input circuit configuration providing a coupling section signal representing the measurement signal, and a high-voltage-side control unit for driving the input circuit, a galvanically isolating coupling section for the potential-free transmission of the coupling section signal to an output circuit at low-voltage potential with an output circuit configuration for generating an output signal from the transmitted coupling section signal, an output for the output signal and at least one low-voltage-side control unit for generating control signals, input elements for inputting control commands and/or parameters into the high-voltage-side control unit, a low-voltage-side arrangement of all the input elements provided for the parameterization of the high-voltage-side control unit, exclusively in a low-voltage circuit, and a galvanically isolating control channel for transmitting the parameters for driving the input circuit.

An isolation amplifier includes an input circuit at high voltage potential with an input for a measurement signal to be transmitted, an input circuit configuration providing a coupling section signal representing the measurement signal, and a high-voltage-side control unit for driving the input circuit, a galvanically isolating coupling section for the potential-free transmission of the coupling section signal to an output circuit at low-voltage potential with an output circuit configuration for generating an output signal from the transmitted coupling section signal, an output for the output signal and at least one low-voltage-side control unit for generating control signals, input elements for inputting control commands and/or parameters into the high-voltage-side control unit, a low-voltage-side arrangement of all the input elements provided for the parameterization of the high-voltage-side control unit, exclusively in a low-voltage circuit, and a galvanically isolating control channel for transmitting the parameters for driving the input circuit.

A circuit that outputs a current which is proportional to an input voltage includes input and output terminals, a comparator, first and second transistors, an inductor, a first resistor, and a differential amplifier. A first input terminal of the comparator is coupled to the input terminal of the circuit, and a second input terminal of the comparator is coupled to an output terminal of the comparator. The first and second transistors are coupled to the output terminal of the comparator. The inductor is coupled to the first and second transistors. The first resistor is coupled between the inductor and the output terminal of the circuit. The differential amplifier includes a first input terminal coupled to a first terminal of the first resistor, a second input terminal coupled to a second terminal to the first resistor, and an output terminal coupled to the first input terminal of the comparator.

A multi-channel switchmode audio amplifier is configured by a programmed processor such that each channel drives separate loads, is connected in parallel or is configured in a bridge-tied mode as well as combinations thereof. In one embodiment, amplifier channels that are connected in parallel have power amplifiers that are driven with signals from a single modulator. A feedback circuit and error amplifier from one channel controls the modulated signal that is applied to each parallely connected amplifier channel. Current feedback circuits for parallely connected amplifier channels are eliminated by tightly controlling the timing of switching in the power amplifier output stages.

Disclosed herein are implantable medical devices (IMDs) including a receiver and a battery, and methods for use therewith. The receiver includes first and second differential amplifiers, each of which monitors for a predetermined signal within a frequency range and drains power from the battery while enabled, and while not enabled drains substantially no power from the battery. To remove undesirable input offset voltages, each of the differential amplifiers, while enabled, is selectively put into an offset correction phase during which time the predetermined signal is not detectable by the differential amplifier. At any given time at least one of the first and second differential amplifiers is enabled without being in the offset correction phase so that at least one of the differential amplifiers is always monitoring for the predetermined signal. In this manner, the receiver is never blind to signals, including the predetermined signals, sent by another IMD.