Qualcomm Incorporated

Debesh Bhatta

Jeffrey Mark Hinrichs

Andrew Weil

Wenjing Yin

John Abcarius

Karthik Nagarajan

Kevin Jia-Nong Wang

Shitong Zhao

Haibo Fei

Hui Wang

Shyam Sivakumar

Christian Venerus

Chenling Huang

Jaswinder Singh

Deping Huang

Robert Martin Ondris

Sulin Li

Certain aspects of the present disclosure provide a relatively compact frequency-locked loop (FLL) using a discrete-time integrator. For certain aspects, the FLL also includes a supplemental oscillator and other circuitry that allows for saving the FLL frequency when a reference clock will be disconnected, maintaining a similar frequency during disconnection, and restoring the FLL frequency when the reference clock is reconnected. One example FLL circuit generally includes: an encoder; a combiner comprising a first input coupled to an output of the encoder; a digital-to-analog converter (DAC) comprising an input coupled to an output of the combiner; a discrete-time integrator comprising an input coupled to an output of the DAC; a voltage-controlled oscillator (VCO) comprising a control input coupled to an output of the discrete-time integrator; and a counter comprising an input coupled to an output of the VCO and comprising an output coupled to a second input of the combiner.

Compact frequency-locked loop architecture for digital clocking

A low-voltage differential signaling receiver is provided that amplifies a differential input voltage to produce a differential output voltage. A signal distortion circuit that detects a distortion in a differential output voltage to assert a signal detection signal that adjusts a gate voltage of a pair of load transistors to reduce the distortion. The load transistors are selectively diode connected to reduce power consumption.

Low-power low-voltage differential signaling receiver with signal distortion correction

An aspect of the disclosure relates to a reference voltage generator, including: a first field effect transistor (FET) including a first threshold voltage; a second FET including a second threshold voltage different than the first threshold voltage; a gate voltage generator coupled to gates of the first and second FETs; a first current source coupled in series with the first FET between first and second voltage rails; a second current source; and a first resistor coupled in series with the second current source and the second FET between the first and second voltage rails, wherein a reference voltage is generated across the first resistor.

Reference voltage generator based on threshold voltage difference of field effect transistors

An oscillator including a switched capacitor configured to generate a sawtooth or ramp voltage in response to a switched capacitor drive signal; a low pass filter (LPF) configured to filter the sawtooth or ramp voltage to generate a filtered voltage; a reference voltage generator configured to generate a reference voltage; an integrator configured to integrate a difference between the sawtooth or ramp voltage and the reference voltage to generate a frequency control signal; a voltage controlled oscillator (VCO) configured to generate a first clock based on the frequency control signal; a frequency divider configured to frequency divide the first clock to generate a second clock; and a switched capacitor driver configured to generate the switched capacitor drive signal in response to the second clock. The oscillator may also include a switched capacitor sampler to sample the sawtooth or ramp voltage, wherein the filtered voltage is based on the sampled voltage.

Resistor-capacitor oscillator (RCO) with digital calibration and quantizaton noise reduction

Certain aspects of the present disclosure provide apparatus and techniques for digital-to-analog conversion. One example apparatus generally includes a first digital-to-analog converter (DAC) having an input coupled to a digital input node of the apparatus, a second DAC, a digital processor coupled between the digital input node and an input of the second DAC, and a combiner coupled to the first DAC and the second DAC.

Partitioned digital-to-analog converter system

Certain aspects of the present disclosure are directed to a digital-to-analog converter (DAC) system. The DAC system generally includes a first current-steering DAC having a positive output, a negative output, and a bypass output; a common-mode (CM) path coupled between the positive and negative outputs; and a CM current compensation path coupled to the CM path.

Digital-to-analog converter (DAC) with common-mode correction

In some aspects, a method for phase multiplexing includes receiving a plurality of phases, selecting one of the plurality of phases based on a select signal using a multiplexer, and outputting the selected one of the plurality of phases at an output of the multiplexer. The method also includes gating the output of the multiplexer during a glitch at the output of the multiplexer.

Glitch free phase selection multiplexer enabling fractional feedback ratios in phase locked loops

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 switched capacitor circuit includes a first capacitor coupled in series with a second capacitor in a first mode of operation across differential output terminals of a circuit. The first capacitor and the second capacitor are coupled in an anti-parallel layout in a second mode of operation. The switched capacitor circuit also includes a third capacitor coupled on a first side to a common node of the first capacitor and the second capacitor. The third capacitor is further coupled on a second side to a current source control voltage in the first mode of operation, and coupled between a bias reference voltage and a common mode reference voltage in the second mode of operation.

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San Diego, CA, United States of America

Debesh Bhatta