Altera Corporation

Kazi Asaduzzaman

Sergey Yuryevich Shumarayev

Tim Tri Hoang

Wilson Wong

Rakesh H Patel

Shou-Po Shih

Thungoc M Tran

Simardeep Maangat

Wanli Chang

Tin H Lai

Mei Luo

Leon Zheng

Mian Z Smith

Kang-Wei Lai

Ninh D Ngo

A circuit includes a phase detector circuit and a data detection circuit. The phase detector circuit generates first and second phase detection signals based on a data signal and a periodic signal. The data detection circuit includes logic circuitry that generates a logic signal based on the first and second phase detection signals. The data detection circuit also includes a plurality of delay elements that generate a series of delayed detection signals based on the logic signal. The data detection circuit generates a data detection signal indicating when the data signal contains data based on the series of delayed detection signals.

Circuits and methods for data detection

An integrated circuit ('IC') may include clock and data recovery ('CDR') circuitry for recovering data information from an input serial data signal. The CDR circuitry may include a reference clock loop and a data loop. A retimed (recovered) data signal output by the CDR circuitry is monitored by other control circuitry on the IC for a communication change request contained in that signal. Responsive to such a request, the control circuitry can change an operating parameter of the CDR circuitry (e.g., a frequency division factor used in either of the above-mentioned loops). This can help the IC support communication protocols that employ auto-speed negotiation.

Clock and data recovery circuitry with auto-speed negotiation and other possible features

An integrated circuit ('IC') may include clock and data recovery ('CDR') circuitry for recovering data information from an input serial data signal. The CDR circuitry may include a reference clock loop and a data loop. A retimed (recovered) data signal output by the CDR circuitry is monitored by other control circuitry on the IC for a communication change request contained in that signal. Responsive to such a request, the control circuitry can change an operating parameter of the CDR circuitry (e.g., a frequency division factor used in either of the above-mentioned loops).

A circuit includes a phase detector circuit, a phase frequency detector circuit, a data detection circuit, a multiplexer circuit, and a clock signal generation circuit. The phase detector circuit is operable to generate a first phase detection signal based on a data signal and a first periodic signal. The phase frequency detector circuit is operable to generate a second phase detection signal based on second and third periodic signals. The data detection circuit is operable to generate a data detection signal based on the first phase detection signal. A multiplexer circuit is operable to provide one of the first and the second phase detection signals as a selected signal based on the data detection signal. The periodic signal generation circuit is operable to cause adjustments to phases of the first and the second periodic signals based on the selected signal.

Techniques for adjusting periodic signals based on data detection

Methods and apparatus are provided for generating a clock signal with relatively high bandwidth and relatively low phase noise. A circuit of the invention can include a pair of transistors serially coupled between a signal of relatively high voltage and a source of relatively low voltage, where a voltage of the signal of relatively high voltage can vary according to a voltage of a variable control signal. A gate of one of the pair of transistors can be coupled to an input clock signal, and an output node between the pair of transistors can be coupled to an output clock signal. The circuit can also include a third transistor, whose drain and source are coupled to the output clock signal, and whose gate can be coupled to a gear input signal. This circuit can advantageously operate under at least two different gears, each with different bandwidth and phase noise characteristics.

Voltage-controlled oscillator methods and apparatus

Techniques are provided for compensating for phase and timing delays in clock signals generated by phase-locked loops and delay-locked loops on integrated circuits. Circuit elements coupled in a feedback loop of a locked circuit can compensate for the timing and phase delays between an input pin and an output pin. Other circuit elements coupled in the feedback loop of a locked circuit can compensate for the delay between an input pin and a destination circuit element. Still other circuit elements coupled in an input reference path of a locked circuit preserve a timing relationship between input clock and input data signals. A clock signal and a data signal received at a destination circuit element have the same phase and timing relationship that exists between the input clock and input data signals at input pins.

Techniques for compensating delays in clock signals on integrated circuits

A feedback loop, such as a phase-locked loop, on an integrated circuit has a detector, a charge pump, and a loop filter. The charge pump adjusts its output current in response to variations in a process of the integrated circuit to reduce variations in the loop bandwidth. The charge pump also adjusts its output current in response to variations in a resistance of a resistor in the loop filter to reduce variations in the loop bandwidth. The charge pump can also adjust its output current in response to variations in a temperature of the integrated circuit to reduce variations in the loop bandwidth. A delay-locked loop on an integrated circuit has a phase detector and a charge pump. The charge pump adjusts its output current in response to variations in the temperature and the process of the integrated circuit to reduce changes in the loop bandwidth.

Loop circuits that reduce bandwidth variations

Serial data transmitter circuitry on a PLD includes a number of features that enable the transmitter to support many different communication protocols under a wide range of circuit conditions. Examples of features that the transmitter may include are (1) multiple pre-emphasis circuits of selectable strength and polarity, (2) selectable VOD, (3) selectable slew rate, (4) calibratable termination, (5) selectable common mode voltage, and (6) electrical idle mode.

High-speed serial data transmitter architecture

Clock data recovery (CDR) circuitry can be provided with dynamic support for changing data rates caused by the interfacing of different protocols. The CDR circuitry, which operates in reference clock mode and data mode, can be controlled by two control signals that signal the CDR circuitry to automatically switch between reference clock mode and data mode, to operate only in reference clock mode, or to operate only in data mode. The control signals can be set by a programmable logic device (PLD), by circuitry external to the PLD, or by user input. A dynamically adjustable parts per million (PPM) detector can also be provided in the CDR circuitry to signal when processing of data during the reference clock mode is completed.

Clock data recovery circuitry with dynamic support for changing data rates and a dynamically adjustable PPM detector

Techniques are provided for dynamically reconfiguring programmable circuit blocks on integrated circuits during user mode. First configuration bits are loaded from first configuration scan registers into second configuration scan registers during configuration mode. The first configuration bits are used to configure programmable settings of a programmable circuit block. During user mode, second configuration bits are transmitted from a pin to the second configuration scan registers without transferring the second configuration bits through the first configuration scan registers. The second configuration bits are used to reconfigure the programmable settings of the programmable circuit block during the user mode. Also, phase shift circuitry can dynamically shift the phase of an output clock signal by selecting a different input clock signal. The phase shift circuitry has a delay circuit that allows the phase of a high frequency clock signal to be shifted without causing glitches in the clock signal.

Techniques for reconfiguring programmable circuit blocks

Clock data recovery (CDR) circuitry or phase locked loop (PLL) circuitry can be provided with a dynamically adjustable bandwidth. One CDR circuit or PLL circuit can be provided to support multiple systems or protocols, multiple parameter requirements for a given system or protocol, and changes in the input frequency or data rate within a given system or protocol. The parameters can include jitter (e.g., jitter tolerance, jitter transfer, jitter generation), source of dominant noise, and lock time. Control signals can be used to dynamically adjust the bandwidth of the CDR circuitry or PLL circuitry while the circuitry is processing data. The control signals can be set by a PLD, by a processor, by circuitry external to the PLD, or by user input.

Clock data recovery circuitry and phase locked loop circuitry with dynamically adjustable bandwidths

Clock and data recovery circuitry is provided that is used in integrated circuits such as programmable logic device integrated circuits. The clock and data recovery circuitry may recover digital data and an embedded clock from a high-speed differential input data stream. The clock and data recovery circuitry may have automatic mode switching capabilities. When operated in reference mode, the clock and data recovery circuit may use a first phase-locked loop to lock onto a reference clock. When operated in data mode, the clock and data recovery circuit may use a second phase-locked loop to lock onto the phase of the differential data stream. A control circuit may automatically switch the clock and data recovery circuit between the reference mode and the data mode. Override signals may be used to force the clock and data recovery circuit out of the automatic mode and into either the reference or data mode.

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Fremont, CA, United States of America

Kazi Asaduzzaman