摘要:
The various components of transceiver circuitry on an integrated circuit are put together in various ways for purposes of being supplied with power to help prevent noise propagation between the groups. In the case of multi-channel transceiver circuitry there can be various amounts of power supply sharing between similar groups in multiple channels.
摘要:
Wide range and dynamically reprogrammable CDR architecture recovers an embedded clock signal from serial input data with a wide range of operating frequencies. In order to support a wide range of data rates, the CDR architecture includes multiple operating parameters. These parameters include various pre/post divider settings, charge pump currents, loop-filter and bandwidth selections, and VCO gears. The parameters may be dynamically reprogrammed without powering down the circuitry or PLD. This allows the CDR circuitry to switch between various standards and protocols on-the-fly.
摘要:
Methods and circuits for automatic adjustment of equalization are presented that improve the quality of equalization for input signals with varying amplitudes. The methods and circuits may be used in Decision Feedback Equalization (DFE) circuits to maintain a constant equalization boost amplitude despite variations in input signal amplitude. The equalization circuitry measures the amplitude of the equalization input signal and computes tap coefficients to maintain a desired level of boost amplitude. Tap coefficients may be automatically adjusted by the equalization circuitry.
摘要:
Methods and circuits are presented for providing equalization, including decision feedback equalization (DFE), to high data-rate signals. Half-rate delay-chain circuitry produces delayed samples of an input signal using two or more delay-chain circuits operating at a fraction of the input signal data-rate. Two delay-chain circuits operating at one-half the input signal data-rate may be used. More generally, n delay-chain circuits operating at 1/n the input signal data-rate may be used. Multiplexer circuitry combines the outputs of the delay-chain circuits to produce an output signal including samples of the input signal at the input signal data-rate. Duplicate path DFE circuitry includes two paths used to provide DFE equalization while reducing the load of the DFE circuitry on the circuitry that precedes it. A first path produces delayed samples of a DFE signal, while a second path produces the DFE output signal from the delayed samples.
摘要:
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.
摘要:
Equalization circuitry for receiving a digital data signal includes both feed-forward equalizer (“FFE”) circuitry and decision-feedback equalizer (“DFE”) circuitry. The FFE circuitry may be used to give the DFE circuitry a signal that is at least minimally adequate for proper start-up of the DFE circuitry. Thereafter, more of the burden of the equalization task may be shifted from the FFE circuitry to the DFE circuitry.
摘要:
Serial data signal receiver circuitry for inclusion on a PLD includes a plurality of equalizer circuits that are connected in series and that are individually controllable so that collectively they can compensate for a wide range of possible input signal attenuation characteristics. Other circuit features may be connected in relation to the equalizer circuits to give the receiver circuitry other capabilities. For example, these other features may include various types of loop-back test circuits, controllable termination resistance, controllable common mode voltage, and a controllable threshold for detection of an input signal. Various aspects of control of the receiver circuitry may be programmable.
摘要:
Equalizer circuitry on an integrated circuit (“IC”) includes a plurality of NMOS equalizer stages connected in series. Each NMOS stage may include folded active inductor circuitry. Each NMOS stage may also include various circuit elements having controllably variable circuit parameters so that the equalizer can be controllably adapted to perform for any of a wide range of high-speed serial data signal bit rates and other variations of communication protocols and/or communication conditions. For example, each NMOS stage may be programmable to control at least one of bandwidth and power consumption of the equalizer circuitry. The equalizer may also have a first PMOS stage that can be used instead of the first NMOS stage in cases in which the voltage of the incoming signal to be equalized is too low for an initial NMOS stage.
摘要:
Deserializer circuitry for high-speed serial data receiver circuitry on a programmable logic device (“PLD”) or the like includes circuitry for converting serial data to parallel data having any of several data widths. The circuitry can also operate at any frequency in a wide range of frequencies. 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).
摘要:
A programmable logic device includes high-speed serial interface (“HSSI”) circuitry that employs one or more clock signals. In addition to use of these clock signals in the HSSI circuitry, circuitry is provided for allowing at least one of these signals to be distributed throughout the PLD core circuitry, e.g., for use as an additional clock signal in the PLD core. Clock distribution is preferably done in a low-skew way.