Xilinx, Inc.

Adebabay M Bekele

Parag Upadhyaya

Atul V Ghia

Vasisht Mantra Vadi

Suresh M Menon

Steven P Young

Mayank Raj

Didem Z Turker Melek

Yohan Usthavia Frans

Hare Krishna Verma

Philip D Costello

Chuan Xie

Xuewen Jiang

Zhaowen Wang

Sandeep Kumar

Sukruth Pattanagiri Giriyappa

Zhaoyin D Wu

Philip M Freidin

Warren E Cory

Paul T Sasaki

Jing Jing

Aman Sewani

Santiago G Asuncion

Some examples described herein provide for controlling output modulation amplitude for optoelectronic devices. In an example, a method includes transmitting a data pattern to an optical modulator device. The method also includes identifying, for each heater control value of a plurality of heater control values for a heater thermally coupled with the optical modulator device, an optical modulation amplitude corresponding to the heater control value based on a corresponding photodiode current value identified while transmitting the data pattern. The method also includes determining a maximum optical modulation amplitude for the optical modulator device based on a plurality of optical modulation amplitudes corresponding to the plurality of heater control values according to the identifying. The method also includes controlling the heater based at least in part on the determined maximum optical modulation amplitude that has been modified according to scaling maximum photodiode current values.

Methods and apparatuses for wavelength locking for optical wavelength division multiplexed micro-ring modulators

Some examples described herein provide for controlling output modulation amplitude for optoelectronic devices. In an example, a method includes transmitting a first data pattern to an optical modulator device. The method also includes determining, while transmitting the first data pattern and for each heater control value of a plurality of heater control values for a heater, a photodiode current value associated with the optical modulator device to generate a plurality of photodiode current values corresponding to the plurality of heater control values. The method also includes determining a maximum optical modulation amplitude for the optical modulator device based at least in part on the plurality of photodiode current values corresponding to the plurality of heater control values. The method also includes controlling the heater for the optical modulator device based on the maximum optical modulation amplitude.

Methods and apparatuses for maximizing output modulation amplitude for optical wavelength division multiplexed micro-ring modulators

Phase-locked loop circuitry generates an output signal based on transformer based voltage controlled oscillator (VCO) circuitry. The VCO circuitry includes upper band circuitry including first oscillation circuitry, a first harmonic filter circuitry coupled to the first oscillation circuitry, and a first selection transistor coupled to the first harmonic filter circuitry and a current source. The first harmonic filter circuitry filters the output signal. The lower band circuitry includes second oscillation circuitry, a second harmonic filter circuitry coupled to the second oscillation circuitry, and a second selection transistor coupled to the second harmonic filter circuitry and the current source. The second harmonic filter circuitry filters the output signal.

Wide frequency range voltage controlled oscillators

Transformer based voltage controlled oscillator circuitry for phase-locked loop circuitry includes upper band circuitry and lower band circuitry. The upper band circuitry operates in a first frequency range and includes a first capacitor array having a variable capacitance. The lower band circuitry operates in a second frequency range and includes a second capacitor array having a variable capacitance. The first frequency range higher than the second frequency range. In a first operating mode, the first capacitor array has a first capacitance value and the second capacitor array has a second capacitance value. In a second operating mode, the second capacitor array has a third capacitance value different than the second capacitance value.

Apparatus and associated methods relate to implementing an analog auxiliary clock and data recovery (CDR) path to provide a high bandwidth CDR in a transceiver that supports both PAM4 and NRZ signaling. In an illustrative example, the auxiliary CDR path may include a phase-frequency detector (PFD)-based phase-locked loop (PLL) and a phase detector (PD)-based PLL. When the PFD-based PLL is locked to a reference clock signal of the transceiver, the PFD-based PLL may be then disabled and the PD-based PLL may be then enabled. Implementing the auxiliary CDR path may advantageously enable the transceiver to implement much larger parts per million (ppm) acquisition and tracking, and thus enable the transceiver to advantageously support new standards such as Peripheral Component Interconnect Express (PCIe) 5.0 and PCIe 6.0, for example.

Flexible wide-range and high bandwidth auxiliary clock and data recovery (CDR) circuit for transceivers

Apparatus and associated methods relate to automatically generating a data structure representation of an on-chip inductive-capacitive (LC) tank circuit by determining parasitic inductances in each of the segments of conductive paths that connect a main inductor to one or more selectable VCO components such as capacitors and varactors, for example. In an illustrative example, one or more of the selectable VCO components may be arranged, when selected, to form a parallel resonant LC tank with the main inductor. A method may include defining nodes aterminating each of the segments along the conductive paths between the main inductor terminals and a drive circuit. By modelling the paths as multi-port inductors and transformers, resonant frequency of the VCO may be more accurately predicted by simulation.

Multi-port inductors and transformers for accurately predicting voltage-controlled oscillator (VCO) frequency

A voltage-controlled oscillator (VCO) includes an inductor-capacitor (LC) tank circuit, tuning circuitry, and a plurality of first varactors. The LC tank circuit is configured to produce an oscillating signal and is operable in a plurality of frequency bands. The tuning circuitry is configured to tune the LC tank circuit to operate in a first frequency band of the plurality of frequency bands based at least in part on a temperature of the VCO. The plurality of first varactors are coupled to the LC tank circuit for tuning the oscillating signal to a target frequency within the first frequency band based on a control voltage.

Temperature-dependent phase-locked loop (PLL) reset for clock synthesizers

In an example, a phase-locked loop (PLL) circuit includes an error detector operable to generate an error signal; an oscillator operable to provide an output signal having an output frequency based on the error signal and a frequency band select signal, the output frequency being a frequency multiplier times a reference frequency; a frequency divider operable to divide the output frequency of the output signal to generate a feedback signal based on a divider control signal; a sigma-delta modulator (SDM) operable to generate the divider control signal based on inputs indicative of an integer value and a fractional value of the frequency multiplier, the SDM responsive to an order select signal operable to select an order of the SDM; and a state machine operable to, in an acquisition state, generate the frequency band select signal and set the order of the SDM.

Reconfigurable fractional-N frequency generation for a phase-locked loop

An example a phase-locked loop (PLL) circuit includes a sampling phase detector configured to receive a reference clock and a feedback clock and configured to supply a first control current and a pulse signal. The PLL further includes a charge pump configured to generate a second control current based on the first control current and the pulse signal. The PLL further includes a loop filter configured to filter the second control current and generate an oscillator control voltage. The PLL further includes a voltage controlled oscillator (VCO) configured to generate an output clock based on the oscillator control voltage. The PLL further includes a frequency divider configured to generate the reference clock from the output clock.

Phase-locked loop having sampling phase detector

An example phase-locked loop (PLL) circuit includes a voltage controlled oscillator (VCO) configured to generate an output clock based on an oscillator control voltage, a sub-sampling phase detector configured to receive a reference clock and the output clock, and a phase frequency detector configured to receive the reference clock and a feedback clock. The PLL circuit includes a charge pump configured to generate a charge pump current, a multiplexer circuit configured to select either output of the sub-sampling phase detector or output of the phase frequency detector to control the charge pump, and a lock detector configured to receive the reference clock, the feedback clock, and the output of the phase frequency detector to control the multiplexer. The PLL circuit includes a loop filter configured to filter the charge pump current and generate the oscillator control voltage, and a frequency divider configured to generate the reference clock from the output clock.

Phase-locked loop having sub-sampling phase detector

Voltage-controlled oscillation is described. In an apparatus therefor, an inductor has a tap and has or is coupled to a positive-side output node and a negative side output node. The tap is coupled to receive a first current. A coarse grain capacitor array is coupled to the positive-side output node and the negative side output node and is coupled to respectively receive select signals. A varactor is coupled to the positive-side output node and the negative side output node and is coupled to receive a control voltage. The varactor includes MuGFETs. A transconductance cell is coupled to the positive-side output node and the negative side output node, and the transconductance cell has a common node. A frequency scaled resistor network is coupled to the common node and is coupled to receive the select signals for a resistance for a path for a second current.

Voltage controlled oscillator including MuGFETS

One embodiment of an integrated circuit includes a local circuit block, a first power supply for supplying power to a first terminal of the local circuit block, a second power supply for supplying power to a second terminal of the local circuit block, a first transmission gate coupled between the second terminal of the local circuit block and a current path from the second power supply, and a second transmission gate coupled between the current path from the second power supply and a gate of a p-type metal-oxide-semiconductor (PMOS) transistor in the first transmission gate, the second transmission gate including a single transistor.

Method and apparatus for powering down a dual supply current source

A method and apparatus for dividing clock frequencies are disclosed. For example, a circuit according to one embodiment of includes a high-speed divider and a plurality of programmable dividers cascading with the high-speed divider, wherein the plurality of programmable dividers are of a lower speed than the high-speed divider.

Method and apparatus for dividing clock frequencies

A clock distribution network having: a backbone clock signal line configured to provide a differential clock signal; multiple branches coupled to the backbone clock signal line for distributing the differential clock signal to multiple programmable function elements; a first leaf node coupled to a first branch, where the first leaf node is configured to provide the differential clock signal to a first programmable function element; and a second leaf node coupled to a second branch, where the second leaf node is configured to provide a single ended clock signal derived from the differential clock signal to a second programmable function element.

Integrated circuit having embedded differential clock tree

A clock distribution network having: a main trunk configured to provide a differential clock signal; a plurality of branches coupled to the main trunk for distributing the differential clock signal to a plurality of circuit elements on the integrated circuit; and a plurality of switches coupling the main trunk to the plurality of branches.

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San Jose, CA, United States of America

Adebabay M Bekele