Qualcomm Incorporated

Chenling Huang

Matthew David Sienko

Haibo Fei

Jingxue Lu

Karthik Nagarajan

Debesh Bhatta

Sungmin Ock

A temperature-compensated low-pass filter includes a differential amplifier that controls a first transistor to pass a subthreshold current through the transistor to charge a capacitor with low-pass-filtered output voltage. A second transistor has a first terminal coupled to an input terminal of the low-pass filter and has a second terminal coupled to a current source conducting a bias current. The differential amplifier also controls the second transistor to conduct the bias current responsive to a difference between a complementary-to-absolute-temperature reference voltage and a voltage of the second terminal of the second transistor.

Temperature-compensated low-pass filter

A method and apparatus for reducing the amount of jitter in a signal are disclosed. In one embodiment a feed-forward loop compares the edges of a reference clock and an input signal, converts a time difference of the compared edges into a voltage signal, and controls a time delay in a voltage controlled delay line in order to reduce or eliminate jitter.

Phase-locked loop output adjustment

A differential class-D amplifier module having common-mode swing limiter circuit is disclosed. The differential class-D amplifier module may include differential class-D amplifier configured to generate differential pulse width modulated (PWM) output signals based on differential input signals and at least a portion of the differential PWM output signals that are fed back to the differential class-D amplifier. The common-mode swing limiter circuit may attenuate one or more common-mode signal components associated with the PWM output signals that may be fed back to input terminals of the differential class-D amplifier.

Swing limiter circuit

In an aspect of the disclosure, a class D power amplifier with an overcurrent protection (OCP) circuit is provided. The class D power amplifier includes a plurality of output transistors, and the OCP circuit is mirrored to at least one output transistor of the plurality of output transistors in a closed-loop feedback configuration for precisely controlling a sensing current of the OCP circuit with respect to an output current of the at least one output transistor. The class D power amplifier with the OCP circuit in the closed-loop feedback configuration mitigates a variation in a current threshold value for triggering interruption of the class D power amplifier.

Overcurrent protection for class D power amplifier

A class D power amplifier is provided. The class D power amplifier includes a class D driver circuit having a plurality of output transistors, at least one active clamp circuit coupled to at least one output transistor of the plurality of output transistors, and at least one filter bank circuit coupled to the at least one active clamp circuit for controlling a voltage of the at least one output transistor. Accordingly, a voltage across a drain node and source node (VDS), a voltage across a gate node and source node (VGS), and a voltage across the gate node and drain node (VGD) of the output transistors is reduced to increase reliability of the power amplifier while consuming less power and utilizing less die area.

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Fremont, CA, United States of America

Chenling Huang