Qualcomm Incorporated

Rf Micro Devices, Inc.

Pradeep Charles Silva

Sherif Galal

Praveen Varma Nadimpalli

Subbarao Surendra Chakkirala

Dongyang Tang

Xinwang Zhang

Vijayakumar Dhanasekaran

Arash Mehrabi

Ramkumar Sivakumar

Qubo Zhou

Derek Schooley

Derick Hugunin

Hanil Lee

ChienChung Yang

Robert Bennett

James Leake

A class-D amplifier including a pulse width modulator including an input configured to receive a first signal based on an input signal, and an output configured to generate a pulse width modulated (PWM) signal; an H-bridge including an input coupled to an output of the pulse width modulator and an output coupled to a load, wherein the H-bridge is configured to generate an output signal across the load based on the PWM signal; and a deadtime compensation circuit coupled to the H-bridge, wherein the deadtime compensation circuit is configured to compensate for deadtime distortion in the output signal. The deadtime compensation circuit may be a feedback circuit between an output of the H-bridge and an input of the pulse width modulator, a pulse modification circuit at the output of the pulse width modulator, or an offset signal generating circuit providing an offset signal to the pulse width modulator.

Class-D amplifier with deadtime distortion compensation

A power amplifier provides reduction of click and pop in audio applications. The power amplifier includes a first amplifier and an auxiliary amplifier. The auxiliary amplifier is used to ramp the power amplifier output from ground to an offset voltage to reduce the 'click and pop' sound. The first amplifier and the auxiliary amplifier having a shared feedback loop. An output of the first amplifier and an output of the auxiliary amplifier may be switchably coupled to the shared feedback loop. A wave generator controls a switch to couple the first amplifier output or the auxiliary amplifier output to the shared feedback loop.

Audio power amplifier for reduced click and pop (CnP)

Certain aspects of the present disclosure provide a power supply circuit. The power supply circuit generally includes: a switched-mode power supply (SMPS) having an inductive element and a first switch coupled to the inductive element; a feedback path coupled between an output of the SMPS and a control input of the first switch; and a current limit circuit comprising a first capacitive element, a charge circuit coupled to the first capacitive element, a first current source, a first resistive element coupled to the first current source, the capacitive element being coupled to a node between the resistive element and the first current source, a sample-and-hold circuit coupled to the first capacitive element, and a clamp circuit coupled between the sample-and-hold circuit and the feedback path.

Current limiting for a boost converter

A method and an apparatus for operating an electronic sensor and an electronic user input are provided. In one configuration, the apparatus includes a detection circuit configured to recognize a user input voltage generated by an electronic user input and a power supply configured to supply power to a detection circuit continuous without polling. In another configuration, the apparatus includes a port, a first power supply, a second power supply, and a control circuit configured to selectively couple the first power supply or the second power supply to the port based on a state of operation of an electronic sensor coupled to the port.

Headset power supply and input voltage recognition

This disclosure relates generally to radio frequency (RF) amplification devices and methods of limiting an RF signal current. Embodiments of the RF amplification device include an RF amplification circuit and a feedback circuit. The RF amplification circuit is configured to amplify an RF input signal so as to generate an amplified RF signal that provides an RF signal current with a current magnitude. The feedback circuit is used to limit the RF signal current. In particular, a thermal sense element in the feedback circuit is configured to generate a sense current, and thermal conduction from the RF amplification circuit sets a sense current level of the sense current as being indicative of the current magnitude of the RF signal current. To limit the RF signal current, the feedback circuit decreases the current magnitude of the RF signal current in response to the sense current level reaching a trigger current level.

Thermally coupled current limiter

A differential voltage controlled current source generating one or more output currents is based upon a single external resistor. The differential voltage controlled current source may generate an output current that is proportional to a received differential voltage and a bias current with the use of a single external resistor. The technique may be used to generate multiple accurate and process independent current sources. The current sources may be a zero temperature coefficient (ZTC) current, a proportional to absolute temperature (PTAT) current, or an inversely proportional to absolute temperature (NTAT) current. The output of the current sources may be inversely proportional to the resistance of the external resistor.

Method of generating multiple current sources from a single reference resistor

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San Diego, CA, United States of America

Pradeep Charles Silva