Altera Corporation

Joseph Huang

Chiakang Sung

Bonnie I Wang

Yan Chong

Khai Nguyen

Xiaobao Wang

Richard G Cliff

Philip Pan

In Whan Kim

L Todd Cope

Tzung-Chin Chang

Wayne Yeung

Bruce B Pedersen

Bahram Ahanin

William W Leong

James A Watson

Michael H M Chu

David Wolk Mendel

Srinivas T Reddy

Cameron R McClintock

Francis B Heile

Kerry S Veenstra

Gopi Rangan

Gopinath Rangan

Pradeep Nagarajan

Philip Clarke

Wanli Chang

Andrew J Bellis

Christopher F Lane

Sean Shau-Tu Lu

Rina Raman

Andy Louie Lee

Cameron R Mc Clintock

Brian D Johnson

Henry Kim

Fung Fung Lee

Manoj B Roge

Phillip Pan

David Edward Jefferson

Craig S Lytle

Ninh D Ngo

Jonathan Chung

Johnson Tan

Thomas Henry White

Adam J Wright

Peter Boyle

Robert R N Bielby

Eric Choong-Yin Chang

Surgey Y Shumarayev

Myron Wai Wong

Ning Xue

Nitin Prasad

Sanjay K Charagulla

Robert R Bielby

Robert Richard Noel Bielby

Bonnie L Wang

David Lewis

Tony K Ngai

Hong Shi

Zhe Li

Ket Chiew Sia

Ee Mei Ooi

Kin Hong Au

Xiabao Wang

By Louis Leong, Legal Representative

William Leong, Deceased

Bruce B Pendersen

Im Whan Kim

Chiakang Song

Boonie I Wang

A buffer circuit with an adjustable reference voltage is presented. The buffer circuit with adjustable reference voltage has an input buffer circuit that is connected to a data input and a reference voltage. The output of the input buffer circuit is connected an eye monitor circuit that generates a transition signal based on a number of transitions of an output of the input buffer circuit. The output from the eye monitor circuit is that processed by a calibration control circuit that transmits a selection signal to a multiplexer. The multiplexer selects a level of the reference voltage based on the selection signal from the calibration control circuit.

On-die input reference voltage with self-calibrating duty cycle correction

Methods and apparatus for providing either high-speed, or lower-speed, flexible inputs and outputs. An input and output structure having a high-speed input, a high-speed output, a low or moderate speed input, and an low or moderate speed output is provided. One of the input and output circuits are selected and the others are deselected. The high-speed input and output circuits are comparatively simple, in one example having only a clear signal for a control line input, and are able to interface to lower speed circuitry inside the core of an integrated circuit. The low or moderate speed input and output circuits are more flexible, for example, having preset, enable, and clear as control line inputs, and are able to support JTAG boundary testing. These parallel high and lower speed circuits are user selectable such that the input output structure is optimized between speed and functionality depending on the requirements of the application.

Programmable high-speed I/O interface

Method and circuitry for implementing high speed multiple-data-rate interface architectures for programmable logic devices. The invention partitions I/O pins and their corresponding registers into independent multiple-data rate I/O modules each having at least one pin dedicated to the strobe signal DQS and others to DQ data signals. The modular architecture facilitates pin migration from one generation of PLDs to the next larger generation.

Multiple data rate interface architecture

Systems and methods are disclosed for calibrating a Data Strobe (DQS) enable/disable signal and for tracking the timing of the DQS enable/disable signal with respect to changes in voltage and temperature (VT) in order to improve the timing margin of the DQS enable/disable signal in programmable devices using Double Data Rate (DDR) memory. In an exemplary embodiment, the system includes a gating circuit, a sampling circuit, and a delay chain tracking circuit. The gating circuit receives a DQS enable signal and a input DQS signal, calibrates the DQS enable signal based on an amount of delay, and outputs the calibrated DQS signal. The sampling circuit provides the amount of delay to the gating circuit based on a sampling clock. The delay chain tracking circuit maintains the timing of the calibrated DQS enable signal over a plurality of clock cycles based on the sampling clock and a leveling clock.

Circuit design technique for DQS enable/disable calibration

An integrated circuit may include a memory controller that interfaces with memory via one or more ports. A given port may be coupled to a comparator that receives data signals from the memory and a reference voltage signal and produces a corresponding output signal that identifies whether the data signals are logic one signals or logic zero signals. The memory controller may include detection circuitry coupled to the port that produces a target reference voltage signal for calibration of the reference voltage signal. The memory controller may include circuitry that produces the reference voltage signal based on control signals received from control circuitry. The control circuitry may generate the control signals to calibrate the reference voltage signal based on the target reference voltage.

Systems and methods for memory controller reference voltage calibration

An integrated circuit in a multi-chip package is provided. The integrated circuit may include adjustable interface circuitry configured to interface with other off-chip components. In particular, the adjustable interface circuitry may include a microbump input-output buffer operable to drive signals off of the integrated circuit and operable to receive signals from other integrated circuits in the multi-chip package via a microbump. The microbump input-output buffer may include output buffers and input buffers. The output buffers may have programmable drive strengths and may each be selectively switched in and out of use depending on the desired application. Each output buffer may include a level shifter, a buffer circuit, and multiple inverter-like circuits each of which can be turned on or off to adjust the drive strength of that output buffer.

Adjustable drive strength input-output buffer circuitry

A circuit-includes a delay locked loop (DLL), a calibration circuit and an output delay chain controlled by the calibration circuit. The DLL comprises a plurality of series-coupled first delay elements, each of which has substantially the same first delay. The calibration circuit comprises a plurality of series-coupled second delay elements, each of which has substantially the same second delay that is less than the first delay, a first delay element, and a circuit for determining the minimum number of second delay elements that are needed to produce the first delay. The output delay chain comprises a plurality of series-coupled second delay elements, an input for receiving the input signal, and a circuit for selectively tapping the output delay chain at a plurality of taps in the output delay chain so as to produce in the input signal different delays of integral multiples of the second delay.

Digital PVT compensation for delay chain

Delay associated with each of two signals along respective transmission paths is accurately measured using a delay measurement circuit that is fabricated in situ on the actual device where the circuitry for propagating the two signals is fabricated. Thus, the measured delay associated with each of the two signals is subject to the same fabrication-dependent attributes that affect the actual circuitry through which the two signals will be propagated during operation of the device. The skew between the two signals is quantified as the difference in the measured delays. Coarse and fine delay modules are defined within the transmission path of each of the two signals. Based on the measured skew between the two signals, the coarse and fine delay modules are appropriately set to compensate for the skew. The appropriately settings for the coarse and fine delay modules can be stored in non-volatile memory elements.

Method and apparatus for minimizing skew between signals

An integrated circuit may include a delay circuit that receives an input signal at a first logic level and produces a delayed output signal at a second logic level at an output terminal. The integrated circuit may include a preset circuit coupled to the delay circuit. The preset circuit may receive the input signal and pre-drive the delayed output signal to an intermediate logic level that lies between the first and second logic levels.

Configurable delay circuitry with compensated delay

A circuit includes a delay locked loop (DLL), a calibration circuit and an output delay chain controlled by the calibration circuit. The DLL comprises a plurality of series-coupled first delay elements each of which has substantially the same first delay. The calibration circuit comprises a plurality of series-coupled second delay elements, each of which has substantially the same second delay that is less than the first delay, a first delay element, and a circuit for determining the minimum number of second delay elements that are needed to produce the first delay. The output delay chain comprises a plurality of series-coupled second delay elements, an input for receiving the input signal, and a circuit for selectively tapping the output delay chain at a plurality of taps in the output delay chain so as to produce in the input signal different delays of integral multiples of the second delay.

Circuits, methods, and apparatus for memory interfaces that compensate for skew between a clock signal and DQ/DQS signals that may be caused by a fly-by routing topology. The skew is compensated by clocking the DQ/DQS signals with a phase delayed clock signal, where the phase delay has been calibrated. In one example calibration routine, a clock signal is provided to a receiving device. A DQ/DQS signal is also provided and the timing of their reception compared. A delay of the DQ/DQS signal is changed incrementally until the DQ/DQS signal is aligned with the clock signal at the receiving device. This delay is then used during device operation to delay a signal that clocks registers providing the DQ/DQS signals. Each DQ/DQS group can be aligned to the clock, or the DQS and DQ signals in a group may be independently aligned to the clock at the receiving device.

Write-leveling implementation in programmable logic devices

Circuits and a method for correcting duty cycle distortions in an integrated circuit (IC) are disclosed. The IC includes a splitter circuit that is coupled to receive a clock signal. The clock signal is split into two different clock signals. One of the clock signals is an inverted version of the other. A delay circuit is coupled to each of the clock signals. Each of the delay circuits generates a delayed version of the corresponding clock signal. A corrector circuit is coupled to receive both the delayed versions of the clock signals. The corrector circuit generates a clock output signal with a corrected duty cycle.

Duty cycle correction circuit for memory interfaces in integrated circuits

A programmable memory interface circuit includes a programmable DLL delay chain, a phase offset control circuit and a programmable DQS delay chain. The DLL delay chain uses a set of serially connected delay cells, a programmable switch, a phase detector and a digital counter to generate a coarse phase shift control setting. The coarse phase shift control setting is then used to pre-compute a static residual phase shift control setting or generate a dynamic residual phase shift control setting, one of which is chosen by the phase offset control circuit to be added to or subtracted from the coarse phase shift control setting to generate a fine phase shift control setting. The coarse and fine phase shift control settings work in concert to generate a phase-delayed DQS signal that is center-aligned to its associated DQ signals.

High performance memory interface circuit architecture

Growing community of inventors

San Jose, CA, United States of America

Joseph Huang