Certain aspects of the present disclosure provide methods and apparatus for implementing an amplification system. The amplification system includes an amplifier comprising differential inputs and an output. The differential inputs include an inverting input and a non-inverting input. The amplification system further includes a feedback path from the output coupled to the inverting input. The feedback path from the output is coupled to at least one of an inverting amplifier or buffer, and the at least one of the inverting amplifier or buffer is further coupled to the non-inverting input.

An apparatus of correcting an offset for a differential amplifier which compensates a direct current (DC) offset voltage in a differential analog signal amplifier using a resistive feedback structure to minimize a deviation and a method thereof are provided. The apparatus includes a differential amplifier that is configured to amplify a common DC voltage input via a first resistor and a second resistor with a predetermined amplification factor to output the amplified voltage. A controller is configured to compare voltages output from both output terminals of the differential amplifier to determine whether to generate an offset. In addition, the offset is corrected using a switching unit coupled in parallel to an input terminal of the differential amplifier in response to detecting a generated offset. The controller is also configured to adjust an asymmetric property of the input terminal of the differential amplifier to correct the generated offset.

A Bridge-Tied Load output self-oscillating class D amplifier includes a comparator receives an input signal from a signal input circuit at a second input terminal and outputs a positive-phase pulse width modulation signal and a reverse-phase pulse width modulation signal by comparing voltages of the two input terminal, first and second switching circuits power-amplifies the reverse-phase pulse width modulation signal and the positive-phase pulse width modulation signal, a first low-pass filter extracts a first output signal from the reverse-phase pulse width modulation signal, a second low-pass filter extracts a second output signal from the positive-phase pulse width modulation signal, a subtractor calculates a difference between the first and second output signals and output a difference signal, and a first feedback circuit feeds back the difference signal to the second input terminal of the comparator.

A half bridge circuit of a class-D amplifier outputs a voltage in accordance with switching of a first switching element and of a second switching element, to a load. A high side gate drive circuit and a low side gate drive circuit respectively drive the first and second switching elements. A bootstrap capacitor connected between the high side gate drive circuit and an output terminal of the half bridge circuit is charged by a charging current from a second direct-current power supply while the first switching element is off. An inductance component for noise suppression, and a voltage limit element that is connected in parallel with the inductance component and is for limiting a voltage that occurs at the inductance component are provided on a path in which the charging current flows.

Certain aspects of the present disclosure provide amplifiers. Certain aspects of the present disclosure provide methods and apparatus for protecting an such amplifiers, for example an audio amplifier, or a delta-sigma modulator from saturation. One example amplifier generally includes an output stage comprising a plurality of transistors; and a feedback network having an input coupled to an output of the output stage and comprising a plurality of integrators connected in series. At least one of the plurality of integrators generally includes an operational amplifier having an input and an output, a first resistive element coupled to the input of the operational amplifier, a capacitive element coupled between the input and the output of the operational amplifier; and a first switch coupled between the input and the output of the operational amplifier. For certain aspects, the amplifier may be a class-D amplifier or a direct digital feedback amplifier (DDFA).

Certain aspects of the present disclosure provide methods and apparatus for dynamically managing the dead time between turning on output power stage transistors in amplifiers, such as audio amplifiers. One example method of operating an amplifier generally includes generating a drive signal based on an input signal; amplifying the drive signal by alternatively driving a first transistor and a second transistor with a time between deactivating the first transistor and activating the second transistor; and adjusting the time based on a parameter of the input signal or the drive signal, during the amplifying. For example, the parameter may include an amplitude of the input signal, a duty cycle of the drive signal, or a duty cycle of a modulated signal (e.g., a pulse-width modulated signal) generated based on the input signal. The input signal may be a digital audio input signal.

An electronic control apparatus that controls actuation of an inductive load includes: a current detector that detect current flowing through the inductive load and outputs a current detection signal in an analog signal; an analog-digital converter that takes in the current detection signal at a fetch timing, and converts the current detection signal into a current detection value; and a controller that calculates a current arithmetic value by executing arithmetic processing for the current detection value, and controls the current based on the current arithmetic value. The controller obtains a sample data value of the current arithmetic value for each of a plurality of fetch timings. The controller calculates a deflection between an ideal value of the current arithmetic value and the sample data value of the current arithmetic value, and learns the fetch timing, causing the deflection with the ideal value of the current arithmetic value to be minimized.

This invention provides compact Power Amplifiers with improved efficiency of the circuitry and improved heat dissipation, together achieved much smaller enclosure size for use in modern installations requiring reduced height such as between the thin flat TV and wall, under the table or on the projector pole or in ceiling box and the like.

This application relates to circuitry for monitoring for instability of an amplifier. The amplifier (100) has a first signal path between an amplifier input (IN.sub.N) and an amplifier output (V.sub.OUT) and a feedback path from the output to form a feedback loop with at least part of the first signal path. A comparator (212) has a first input configured to receive a first signal (IN.sub.N) derived from a first amplifier node which is part of said feedback loop and a second input configured to receive a second signal (IN.sub.P) derived from a second amplifier node which varies with the signal at the amplifier input but does not form part of said feedback loop. The comparator is configured to compare the first signal to the second signal and generate a comparison signal (COMP), wherein in the event of amplifier instability the comparison signal comprises a characteristic indicative of amplifier instability.

A self-oscillating class D amplifier includes an integration circuit configured to integrate an input signal and output a result of the integration as an integrated signal, a comparator configured to receive the integrated signal at an inverting input terminal and output a pulse width modulation signal by comparing voltages of a non-inverting input terminal being grounded and the inverting input terminal, a switching circuit configured to power-amplify the pulse width modulation signal output from the comparator, a low-pass filter configured to extract an amplified output signal from the power-amplified pulse width modulation signal, a first feedback circuit configured to feed back the output signal of the low-pass filter to the inverting input terminal of the comparator, and a second feedback circuit configured to feed back the output signal of the low-pass filter to the integration circuit.