摘要:
Programmable logic device integrated circuitry having differential I/O circuitry is provided. The differential I/O circuitry may include output drivers for providing differential digital output data signals across pairs of output lines. A user may program the I/O circuitry to accommodate different high-speed differential I/O signaling standards. The user may also program the I/O circuitry to provide a desired amount of preemphasis to the output data signals.
摘要:
Programmable logic device integrated circuitry having differential I/O circuitry is provided. The differential I/O circuitry may include output drivers for providing differential digital output data signals across pairs of output lines. A user may program the I/O circuitry to accommodate different high-speed differential I/O signaling standards. The user may also program the I/O circuitry to provide a desired amount of preemphasis to the output data signals.
摘要:
Programmable logic device integrated circuitry having differential I/O circuitry is provided. The differential I/O circuitry may include output drivers for providing differential digital output data signals across pairs of output lines. A user may program the I/O circuitry to accommodate different high-speed differential I/O signaling standards. The user may also program the I/O circuitry to provide a desired amount of preemphasis to the output data signals.
摘要:
The disclosed invention is a technology for producing a recovered clock signal using a multi-mode clock data recovery (CDR) circuit that accommodates a flexible range operating frequencies F and consecutive identical digit requirements CID. In a first mode of operation, a controlled oscillator produces the recovered clock signal, and in a second mode of operation, a phase interpolator produces the recovered clock signal. The multi-mode CDR circuit operates in the first mode if (CID/F) is less than a threshold time value and in the second mode if (CID/F) is greater than the threshold time value.
摘要:
A serial interface for a programmable logic device can be used as a conventional high-speed quad interface, but also allows an individual channel, if not otherwise being used, to be programmably configured as a loop circuit (e.g., a phase-locked loop). This is accomplished by disabling the data loop of clock-data recovery circuitry in the channel, and reconfiguring the reference loop to operate as a loop circuit. In addition, instead of providing a high-speed quad interface having four channels and one or more clock management units (CMUs), a more flexible interface having five or more channels can be provided, and when it is desired to use the interface as a high-speed quad interface, one or more channels can be configured as loop circuits to function as CMUs.
摘要:
The disclosed invention is a technology for producing a recovered clock signal using a multi-mode clock data recovery (CDR) circuit that accommodates a flexible range operating frequencies F and consecutive identical digit requirements CID. In a first mode of operation, a controlled oscillator produces the recovered clock signal, and in a second mode of operation, a phase interpolator produces the recovered clock signal. The multi-mode CDR circuit operates in the first mode if (CID/F) is less than a threshold time value and in the second mode if (CID/F) is greater than the threshold time value.
摘要:
The disclosed invention is a technology for producing a recovered clock signal using a multi-mode clock data recovery (CDR) circuit that accommodates a flexible range operating frequencies F and consecutive identical digit requirements CID. In a first mode of operation, a controlled oscillator produces the recovered clock signal, and in a second mode of operation, a phase interpolator produces the recovered clock signal. The multi-mode CDR circuit operates in the first mode if (CID/F) is less than a threshold time value and in the second mode if (CID/F) is greater than the threshold time value.
摘要:
Circuitry and methods are provided for an LVDS-like transmitter that may be able to DC couple to a receiver having a CML termination scheme. Replacing the common mode voltage source of an LVDS transmitter with a resistive pulldown to ground may allow the transmitter to interface in a DC coupled fashion with a CML receiver. Further, the resistive pulldown may be programmable. This LVDS-like transmitter may be able to support a wider customer base by allowing it to DC couple to a wider range of termination voltage levels, such as CML termination voltage levels.
摘要:
A speed path circuit includes a reference circuit and adjustable drive components that can be turned on or off to vary the speed path in order to meet minimum delay specification for the circuit. In an embodiment, one or more differential amplifiers are used to detect the strength of example circuit elements and generate a reference signal. An optional embodiment includes a mechanism for disconnecting the reference circuit to avoid any DC current drain. The invention may be used in a wide range of integrated circuits and may also be used in a programmable logic device (PLD). Reference circuits may be disconnected from a power source by using programmable logic elements.
摘要:
Programmable logic device circuitry for receiving and/or transmitting a differential signal includes controllable invert circuitry that effectively reverses the polarity of the differential signal. The controllable invert circuitry operates on a single-ended (non-differential) signal that has either been derived from a differential input signal or from which a differential output signal will be derived.