Xilinx, Inc.

Ronan Sean Casey

Declan Carey

Kevin Zheng

Catherine Hearne

Hongtao Zhang

Pedro W Neto

Lokesh Rajendran

Hsung Jai Im

Winson Lin

Chi Fung Poon

Jinyung Namkoong

Ankur Jain

Junho Cho

Kevin Geary

Thomas Mallard

Frantz Stephane Florent Ngankem Ngankem

Yanfei Chen

Ilias Chlis

Embodiments herein describe correcting nonlinearity in a Digital-to-Time Converter (DTC) by relaxing a DTC linearity requirement, which results in the correction being co-adapted with a DTC gain calibration loop which can operate in parallel with a DTC integral nonlinearity (INL) correction loop. In one embodiment, the DTC gain calibration loop and the DTC INL correction loop are constrained when determining a nonlinearity correction code to improve the likelihood they converge. Once determined, the nonlinearity correction code can be combined with an digital code output by a time-to-digital converter (TDC) to generate a phase difference between a reference clock and a feedback clock.

DTC nonlinearity correction

Methods, systems, and apparatus described herein make a multi-level PAM signal (PAM-N signal) at a transmitter using CMOS-based components. By forming the PAM-N signal at the transmitter, receivers do not have to recombine and/or realign multiple signals and only employs a single transmission line channel (or two transmission line channels in differential implementations) to convey the data stream to the receiver from the transmitter.

Ultra-high-speed PAM-N CMOS inverter serial link

Some examples described herein provide for an integrated circuit including a continuous time linear equalizer (CTLE) circuit and a method of operating the integrated circuit. In an example, an integrated circuit includes a transconductance amplifier stage and a transimpedance amplifier stage. The transconductance amplifier stage has a first input node and a first output node. The transconductance amplifier stage includes a first complementary device inverter. The transimpedance amplifier stage has a second input node and a second output node. The first output node is electrically connected to the second input node. The transimpedance amplifier stage includes a second complementary device inverter.

Integrated circuit including a continuous time linear equalizer (CTLE) circuit and method of operation

Apparatus and associated methods relate to targeted digital correction of a predetermined component of inter-symbol interference (ISI) associated with two or more ranks of cascaded track-and-hold (T/H) front-end circuits of a Time-Interleaved analog-to-digital converter (TI-ADC). In an illustrative example, for two T/H circuit ranks of size N and M, the predetermined component to be compensated may be located at (N&#xd7;M)unit interval (UI). A feed forward equalizer (FFE) and/or a decision feedback equalizer (DFE) in a digital signal processing system (DSP) may be then configured to have extra taps and corresponding expanded equalization ranges to mitigate the ISI. Thus, a deterministic ISI component at the N&#xd7;MUI may be digitally corrected by providing equalization with N&#xd7;M taps at low cost to facilitate scaling to higher bit rates.

Dsp cancellation of track-and-hold induced ISI in ADC-based serial links

Apparatus and associated methods relate to a time-interleaved integrating sampling front-end circuit using integrating buffers. In an illustrative example, a circuit may include N sampling layers of circuits, an isampling layer of circuits of the N sampling layers of circuits may include: (a) Xbuffers configured to receive an analog signal, X&#x2265;1, and, (b) Ytrack-and-hold circuits, each track-and-hold circuit of the Ytrack-and-hold circuits is coupled to an output of a corresponding buffer of the X buffers, Y&#x2265;1, at least one buffer of the Xbuffers may include an integrating buffer, N&#x2265;i&#x2265;1. By implementing integrating buffers, a faster linear type of step settling response may be obtained as opposed to a slower exponential type of settling response.

Low power device for high-speed time-interleaved sampling

Apparatus and associated methods relate to providing a regulation loop using a digital representation of a loop error signal along with a flexible multiplying capacitive digital-to-analog converter (MC-DAC) circuit to control one or more power switches (e.g., transistors) delivering required power (including voltage and/or current) to a load circuit. In an illustrative example, the MC-DAC circuit may include a digital-to-analog converter (DAC) configured to selectively couple to two different reference voltages in response to switch control signals generated by a digital filter. A capacitive level shifter may be coupled to the output of the DAC. A re-sampling circuit may be coupled to the output of the capacitive level shifter to generate a gate control signal to control the one or more power switches. The regulation loop may advantageously generate the gate control signal using a substantially reduced die area.

Hybrid multiplying capacitive digital-to-analog converter (MC-DAC) based loop regulation

Apparatus and associated methods relate to a peaking module fabricated on a semiconductor substrate including a follower circuit driving a series peaking circuit-branch, the module configured to extend the bandwidth of a track-and-hold circuit. In an illustrative example, the series peaking circuit-branch may include an inductive element. One or more tracks on a metal interconnect above the semiconductor substrate may form the inductive element, for example. In some examples, one or more peaking modules may be combined creating a customized frequency response. In some examples, one or more combined peaking modules may be adjusted by a controller providing dynamic frequency response customization during operation. The follower circuits may employ constant current biasing and/or constant-gbiasing to provide substantial immunity to process, temperature and voltage variations, for example. Various implementations of series peaking circuit-branch pre-emphasis may advantageously extend overall bandwidth of various circuits (e.g., high-speed track-and-hold circuits).

Programmable buffering, bandwidth extension and pre-emphasis of a track-and-hold circuit using series inductance

The phase interpolator comprises a first charge pump configured to receive a first differential clock signal having a first clock phase, wherein the first charge pump has a first current path and a second current path coupled between a first pull-up current source and a first pull-down current source, wherein the first current path comprises a first NMOS steering switch coupled between a first output node and the first pull-down current source and the second current path comprises a second NMOS steering switch coupled between a second output node and the first pull-down current source; and a second charge pump configured to receive a second differential clock signal having a second clock phase, wherein the second charge pump has a third current path and a fourth current path coupled between a second pull-up current source and a second pull-down current source, and wherein the third current path comprises a third NMOS steering switch coupled between the first output node and the second pull-down current source and the fourth current path comprises a fourth NMOS steering switch coupled between the second node and the second pull-down current source.

Method of implementing a differential integrating phase interpolator

A circuit for controlling output swing in a current-mode logic circuit is described. The circuit comprises a plurality of current-mode logic circuits coupled in series; a first current-mode logic circuit of the plurality of current-mode logic circuits coupled to provide a signal to a second current-mode logic circuit of the plurality of current-mode logic circuits; an amplitude detector coupled to detect an amplitude of the signal received at the second current-mode logic circuit; and a control circuit coupled to the amplitude detector; wherein the control circuit generates an amplitude control signal for a current-mode logic circuit of the plurality of current-mode logic circuits based upon a detected amplitude of the signal received at the second current-mode logic circuit. A method of controlling output swing in a current-mode logic circuit is also disclosed.

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Cork, Ireland

Ronan Sean Casey