Qualcomm Incorporated

Nitz Saputra

Ashok Swaminathan

Dongwon Seo

Behnam Sedighi

Shahin Mehdizad Taleie

Sameer Wadhwa

Bhushan Shanti Asuri

Andrew Weil

Ibrahim Ramez Chamas

Honghao Ji

Negar Rashidi

Jong Hyeon Park

Sang-June Park

Chinmaya Mishra

Vinod Panikkath

Krishnaswamy Thiagarajan

Bo Yang

Ayush Mittal

Haibo Fei

Sameer Vasantlal Vora

Sang Min Lee

Zhilong Tang

Parisa Mahmoudidaryan

Xiahan Zhou

Tonmoy Biswas

Sumant Ramprasad

Xilin Liu

Ping Wing Lai

Eunyung Sung

Chen Jiang

Osama Elhadidy

Peter Gazzerro

Yen-Wei Chang

Sy-Chyuan Hwu

Vinay Kundur

A first inverter in a clock generation circuit is coupled to an input clock signal and has multiple driver slices. Each driver slice includes first transistors that have gates coupled to the input clock signal, second transistors that have sources coupled to rails of a power supply. Each of the second transistors has a drain coupled to a source of one of the first transistors. The second transistors are turned on or turned off based on signaling state of a differential enable signal. A tuning resistor is coupled to the drains of the first transistors and further coupled to an output of the first inverter. A second inverter outputs a quadrature version of the input clock signal and has an input coupled to the output of the first inverter. A first tunable capacitor is coupled to the output of the first inverter.

Hybrid clocking scheme for SERDES physical layer circuits

A clock conditioning circuit includes a duty cycle correction circuit. The duty cycle correction circuit has a first input capacitor, a first self-biasing inverter and a variable capacitor. The first self-biasing inverter has an input coupled to the first input capacitor. The variable capacitor may be coupled to the first input capacitor. The variable capacitor may be configured to receive a first clock signal. A capacitance of the variable capacitor may be programmable by a capacitance control signal.

Programmable self-biasing inverter for correcting duty cycle distortion

Methods and apparatus for sharing digital-to-analog (DAC) converters in a reconfigurable DAC circuit to support two or more transmit chains of a wireless transmitter configured for different radio access technologies (RATs) and/or different transmitter architectures. One example DAC circuit generally includes at least four DACs and a plurality of switches coupled to outputs of the at least four DACs such that the DAC circuit is configured as a multi-channel DAC circuit with at least four channels for a first set of one or more frequency bands and as an interleaved DAC circuit with at least two channels for a second set of one or more frequency bands different from the first set of frequency bands.

Reconfigurable transmit digital-to-analog converter (DAC) circuit

Certain aspects of the present disclosure generally relate to a digital-to-analog converter (DAC) circuit implemented with a dynamic stacked transistor architecture. The DAC circuit generally includes a first current-steering transistor and a second current-steering transistor. The DAC circuit may also include: a first stacked transistor coupled between the first current-steering transistor and a first output of the DAC circuit; a first switch coupled between a gate of the first stacked transistor and a bias voltage node; a second switch coupled between the gate of the first stacked transistor and a voltage rail; a second stacked transistor coupled between the second current-steering transistor and a second output of the DAC circuit; a third switch coupled between a gate of the second stacked transistor and the bias voltage node; and a fourth switch coupled between the gate of the second stacked transistor and the voltage rail.

Digital-to-analog converter (DAC) with dynamic stacked cascode switches

A transmitter includes driver slices coupled to its output. Each driver slice includes a first differential predriver that is selectively enabled and disabled by a first switch based on a control code configuration. A second differential predriver provides a first differential buffered data signal to a first group of driver slices when the second differential predriver is enabled. A second switch enables the second differential predriver when the control code is configured to enable the first differential predriver in at least one driver slice in the first group of driver slices. A third differential predriver provides a second differential buffered data signal to a second group of driver slices when the third differential predriver is enabled. A third switch enables the third differential predriver when the control code is configured to enable the first differential predriver in at least one driver slice in the second group of driver slices.

Low power auto-scalable differential predriver

Methods and apparatus for filtering a signal using a current-mode filter circuit implementing source degeneration. An example filter circuit generally includes an input node; an output node; a power supply node; a first transistor comprising a drain coupled to the input node; a second transistor comprising a drain coupled to the output node and comprising a gate coupled to a gate of the first transistor; a capacitive element coupled between the drain of the first transistor and the power supply node; a first resistive element coupled between the drain and the gate of the first transistor; a first source degeneration element coupled between a source of the first transistor and the power supply node; and a second source degeneration element coupled between a source of the second transistor and the power supply node.

Wideband current-mode low-pass filter circuits

Methods and apparatus for common-mode current removal in a digital-to-analog converter (DAC). An example DAC circuit generally includes a plurality of current-steering cells, a resistor ladder circuit coupled to the plurality of current-steering cells and having a plurality of shunt branches, and an adjustable resistance circuit coupled between middle nodes of the plurality of shunt branches and a reference potential node for the DAC circuit.

Common-mode current removal schemes for digital-to-analog converters

Methods and apparatus for adaptively adjusting a resistance of a resistor network in a digital-to-analog converter (DAC), such as a current-steering DAC for a transmit chain. An example DAC generally includes a plurality of DAC cells. One or more of the DAC cells generally includes a current source and a resistor network. The resistor network includes a plurality of resistive elements, has an adjustable resistance, and is coupled between a power supply rail and the current source. In this manner, the DAC may support a wide range of full-scale currents, while maintaining a higher degeneration voltage and reduced noise and mismatch for a given headroom. For certain aspects, the one or more of the DAC cells further include a plurality of switches (e.g., implemented with PFETs) coupled to one or more of the resistive elements and configured to adjust the resistance of the resistor network.

Resistor network with adaptive resistance for digital-to-analog converter (DAC)

In certain aspects, a method for providing a first drive clock signal and a second drive clock signal to a first sub-digital-to-analog converter (sub-DAC) and a second sub-DAC includes receiving an input clock signal, and dividing the input clock signal to generate a first divided clock signal and a second divided clock signal. The method also includes gating the input clock signal using the first divided clock signal to generate the first drive clock signal, and inputting the first drive clock signal to a clock input of the first sub-DAC. The method further includes gating the input clock signal using the second divided clock signal to generate the second drive clock signal, and inputting the second drive clock signal to a clock input of the second sub-DAC.

Clock driver for time-interleaved digital-to-analog converter

Methods and apparatus for adaptively generating a reference voltage (V) for biasing a switch driver and corresponding switch in a digital-to-analog converter (DAC). The adaptive biasing scheme may be capable of tracking process, voltage, and temperature (PVT) of the DAC. An example DAC generally includes a plurality of DAC cells, each DAC cell comprising a current source, a switch coupled in series with the current source, and a switch driver coupled to a control input of the switch, the switch driver being configured to receive power from a first power supply rail referenced to a reference potential node; a regulation circuit comprising a first transistor coupled between the reference potential node for the DAC and the switch driver in at least one of the plurality of DAC cells; and a Vgeneration circuit coupled to the regulation circuit and configured to adaptively generate a Vfor the regulation circuit.

Adaptive switch biasing scheme for digital-to-analog converter (DAC) performance enhancement

Certain aspects of the present disclosure generally relate to circuitry and techniques for digital-to-analog conversion. One example device for digital-to-analog conversion generally includes: a digital-to-analog converter (DAC) having an input coupled to an input node of the device; a first return-to-zero (RZ) DAC having an input coupled to an input node of the device; and a combiner, wherein an output of the first DAC is coupled to a first input of the combiner, and wherein an output of the first RZ DAC is coupled to a second input of the combiner.

Return-to-zero (RZ) digital-to-analog converter (DAC) for image cancellation

A current digital-to-analog converter includes a binary current-generating section configured to generate a binary-weighted current based on a first set of control signals; a unary current-generating section configured to generate a unary-weighted current based on a second set of control signals; and a current combining circuit configured to add or subtract a reference current and a current generated by a current source of the unary current-generating section using the binary-weighted current.

Apparatus and method for measuring current source mismatches in current-steering DAC by re-using R2R network

An RF-DAC transmitter is provided that includes an in-phase channel, a quadrature-phase channel, a first intermediate-phase channel, and a second intermediate-phase channel. Each channel includes a pair of interleaved RF-DACs for producing a pair of interleaved RF signals and a subtractor.

Digital RF-DAC

A communication circuit may include a first pair of digital-to-analog converters (DACs) coupled to an input of a first mixer and configured to generate first baseband signals. The communication circuit may further include a second pair of DACs coupled to an input of a second mixer and configured to generate second baseband signals. The second baseband signals may be shifted in phase relative to the first baseband signals.

Communication circuit including a transmitter

The present disclosure describes aspects of segmented resistor architecture for digital-to-analog converters (DACs). In some aspects, a DAC circuit is implemented with a first resistor network coupled to a set of binary code-controlled current sources and a second resistor network that includes a resistor coupled between the first resistor network and an output of the DAC circuit. A set of thermometer code-controlled current sources are coupled to a node of the second resistor network and provide varying amounts of current. This current is scaled based on a resistance of the second resistor network's resistor, which is higher than a resistance of the first resistor network and effective to increase a combined output impedance of the first and second resistor networks. The increase of output impedance reduces noise of the resistor networks that transfers to the output of the DAC circuit, thereby improving signal-to-noise performance of the DAC circuit.

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Burlingame, CA, United States of America

Nitz Saputra