Altera Corporation

Integrated Device Technology, Inc.

Shoujun Wang

Tad Kwasniewski

Haitao Mei

Bill W Bereza

Mashkoor Baig

William W Bereza

Sergey Yuryevich Shumarayev

Chong H Lee

Thungoc M Tran

Ramanand Venkata

Arch Zaliznyak

Toan Thanh Nguyen

Yuming Tao

Rakesh H Patel

Shengyuan Zhang

Yu Zhang

Mirza Baig

Yong Wang

Muhammad Usama

Miao Li

Yunfu Yang

Serializer circuitry for high-speed serial data transmitter circuitry on a programmable logic device ('PLD') or the like includes circuitry for converting parallel data having any of several data widths to serial data. The circuitry can also operate at any frequency in a wide range of frequencies, and can make use of reference clock signals having any of several relationships to the parallel data rate and/or the serial data rate. The circuitry is configurable/re-configurable in various respects, at least some of which configuration/re-configuration can be dynamically controlled (i.e., during user-mode operation of the PLD).

Serializer circuitry for high-speed serial data transmitters on programmable logic device integrated circuits

Charge pump circuitry is provided that is insensitive to charge sharing and current mismatch effects. The charge pump circuitry has an output node at which a charge pump output voltage is provided. A first current source charges the output node to increase the output voltage or a second current source discharge the output node to decrease the output voltage. The charge pump circuitry uses a unit-gain op-amp circuit to prevent charge sharing effects from affecting the output voltage when switching between discharging and charging operations. A low-pass filter is used to reduce feedback noise on the output node. A replica feedback circuit prevents current mismatch between the currents produced by the first and second current sources. The first and second current sources may be formed using programmable transistors that are adjusted by static control signals provided by programmable elements to further minimize current mismatch.

Charge pump with reduced current mismatch

A method and circuit for generating an adjustable delay signal is presented, wherein the delay can be linear and monotonic with high resolution delay steps. The circuit utilizes one or more serially coupled delay cells and a load cell. Each delay cell comprises an inverter, a nor-multiplexer, and a programmable capacitor, wherein a first control signal is used to control the operation of the nor-multiplexer and a second control signal is used to control capacitance of the programmable capacitor. Values of the first and the second control signals are selected based on any desired range of total delay time and any desired delay time for a specific application of the circuit.

Linear monotonic delay chain circuit

Methods and circuits are provided for producing phase-adjusted pre-emphasis and equalization. In applications in which little or no phase distortion occurs during signal transmission, propagation, or reception, linear-phase pre-emphasis or equalization can be used to reduce or eliminate phase distortion introduced by the pre-emphasis or equalization. Linear phase, constant group delay FIR filters or circuits may have odd numbers of coefficients symmetrical about the middle coefficient. In applications in which signal phase distortion occurs, linear phase or non-linear phase pre-emphasis or equalization can be used to reduce or compensate for the phase distortion. Phase compensation may be effected using FIR pre-emphasis and equalization filters and circuits. Non-linear phase FIR filters may have different numbers and combinations of coefficients.

Phase-adjusted pre-emphasis and equalization for data communication

Duty cycle correction (DCC) methods and circuits are provided for improving the quality of clock signals and reducing or eliminating duty cycle distortion. The performance of known duty cycle correction circuits, such as cross-coupled inverter or transmission gate DCC circuits, may be improved by coupling two or more DCC circuits in series to form a multi-stage DCC circuit. In multi-stage DCC circuits, the performance and sizing requirements imposed on the individual circuit stages are reduced as compared to single-stage DCC circuit implementations. Good duty cycle correction performance over a wide range of input signal duty cycles may therefore be ensured regardless of the performance of individual stages. Clocked-CMOS DCC circuits are also presented, the circuits operative to produce duty cycle corrected output signals while consuming minimal current and power. The clocked-CMOS DCC circuits include as few as four transistors, and are operative over wide ranges of input signal duty cycles.

Duty cycle correction methods and circuits

A reduced power differential type termination circuit for use in SSTL, HSTL and other transmission line systems reduces power consumption. A differential type termination circuit may comprise first and second nodes for coupling, respectively, to first and second transmission lines; a first impedance coupled between the first transmission line and a third node; a second impedance coupled between the second transmission line and the third node; and a low direct current reference voltage generator for generating a reference voltage applied to the third node. The first and second transmission lines may transmit complimentary signals. The first and second impedances may be symmetric or asymmetric. The first impedance may match the second impedance. The first and second impedances may, respectively, match the impedances of the first and second transmission lines. The first and/or second impedances may include a bidirectional switch, such as a transmission gate, to enable and disable the termination circuit.

Reduced power differential type termination circuit

A built-in, at-speed BERT is provided that may be part of high-speed serial interface circuitry implemented on an integrated circuit. The built-in, at-speed BERT takes advantage of an existing clock data recovery (CDR) dual-loop architecture and built-in self test (BIST) circuitry. The built-in, at-speed BERT provides a low-cost solution for production testing of high-speed serial links, facilitating jitter analysis and evaluation of pre-emphasis and equalization performance. This further allows adaptation of pre-emphasis and equalization.

Built-in at-speed bit error ratio tester

Equalization circuitry that includes an analog equalizer and a decision feedback equalizer (DFE) is provided for high-speed backplane data communication. The analog equalizer reduces the number of taps that are required by the DFE, which lessens the error propagation of the DFE. Furthermore, the DFE includes a summing circuit and flip-flop circuitry. The flip-flop circuitry may be used as part of a phase detector by clock and data recovery circuitry. The summing circuit may further be embedded into the flip-flop circuitry to reduce the feedback path delay, thereby allowing for higher speed operation. The DFE may be extended to multiple taps by including additional flip-flops.

Methods and apparatus for equalization in high-speed backplane data communication

Systems and methods for accurately and quickly simulating link performance of a transceiver operating with any given transmission medium are provided. Accurate and quick link simulations may be provided using a link simulation platform. The link simulation platform may simulate link performance using transceiver behavioral models (e.g., transmitter and receiver behavioral models) that incorporate silicon level parameters, which parameters enable the behavioral models to substantially emulate the actual behavior of the transceiver portions of the link.

Systems and methods for simulating link performance

Switching and repeating applications using an impedance matched source follower improve performance of high speed links such as PCI Express, HDMI, DisplayPort and DVI by reducing attenuation and other degradation of high speed signals, including those with transmit pre-emphasis, by avoiding impedance discontinuities over process, voltage and temperature variations and by driving a broader range of loads, e.g., heavily capacitive loads. A circuit for switching or repeating signals on a single-ended or differential high speed link may comprise a source follower with input and output impedances matched to input and output transmission lines on the high speed link. The source follower is biased by a constant transconductance circuit, an external calibration circuit or other circuit to provide an essentially constant output impedance over process, voltage and temperature variations.

Low-loss impedance-matched source-follower for repeating or switching signals on a high speed link

A reference clock receiver structure according to the invention is provided. The structure preferably includes an input buffer that is formed from a PMOS differentiated pair of transistors and a first supply voltage. The PMOS differential pair receives a pair of differential inputs, and produces a pair of differential outputs. The structure also includes a level shifter that is coupled to receive the pair of differential outputs from the input buffer to provide gain to the pair of differential outputs to form a gained pair of differential outputs. The level shifter that includes a second supply voltage. The second supply voltage may have a smaller magnitude than the first supply voltage. Finally, the structure includes a CMOS buffer that is coupled to receive the gained pair of differential outputs. The CMOS buffer boosts the gained pair of differential outputs and converts the gained differential pair outputs into a single signal.

Reference clock receiver compliant with LVPECL, LVDS and PCI-Express supporting both AC coupling and DC coupling

A dual-mode LVDS/CML transmitter allows a single circuit to operate as either an LVDS transmitter or a CML transmitter. The transmitter mode can be switched by activating or deactivating appropriate circuit elements, and changing the voltage or current produced by appropriate sources or sinks. This flexibility allows a single transmitter to operate well in both AC and DC coupling conditions, and facilitates interoperation with a greater variety of receivers.

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Kanata, Canada

Shoujun Wang