摘要:
A programmable logic device is equipped for low voltage differential signaling (“LVDS”) by providing an LVDS input buffer and/or an LVDS output buffer on the device. I/O pins on the device that are used together in pairs for LVDS can alternatively be used individually for other types of signaling. The LVDS buffers are constructed to give good performance and to meet LVDS specifications despite variations due to temperature, manufacturing process inconsistency, and power supply changes.
摘要:
A programmable input/output circuit for a programmable logic device input/output pin can be configured in a standard I/O mode, or in a reference voltage mode. The circuit includes a tristatable, but otherwise standard I/O buffer as well as a reference voltage clamp circuit. In reference voltage mode, the I/O circuit is tristated, and the reference voltage clamp circuit passes a reference voltage from the I/O pin to a reference voltage bus. In standard I/O mode, the I/O buffer is operational. The reference voltage clamp circuit isolates the I/O pin from the reference voltage bus and may include undervoltage and overvoltage protection to prevent disturbance of the reference voltage bus by an out-of-range I/O signal.
摘要:
A programmable logic device is equipped for low voltage differential signaling (“LVDS”) by providing an LVDS input buffer and/or an LVDS output buffer on the device. I/O pins on the device that are used together in pairs for LVDS can alternatively be used individually for other types of signaling. The LVDS buffers are constructed to give good performance and to meet LVDS specifications despite variations due to temperature, manufacturing process inconsistency, and power supply changes.
摘要:
A circuit provides a programmable phase shift feature, where the phase shift is programmably selectable by a user. This circuitry may be incorporated in a programmable logic device (PLD) or field programmable gate array (FPGA) to provide additional programmability features. The programmable phase shift circuitry may be implemented within a phase locked loop (PLL) or delay locked loop (DLL) circuit. In an implementation, the programmable phase shift circuitry is implemented using two programmable counters.
摘要:
A programmable logic device is equipped for low voltage differential signaling (“LVDS”) by providing an LVDS input buffer and/or an LVDS output buffer on the device. I/O pins on the device that are used together in pairs for LVDS can alternatively be used individually for other types of signaling. The LVDS buffers are constructed to give good performance and to meet LVDS specifications despite variations due to temperature, manufacturing process inconsistency, and power supply changes.
摘要:
A programmable logic device is equipped for low voltage differential signaling (“LVDS”) by providing an LVDS input buffer and/or an LVDS output buffer on the device. I/O pins on the device that are used together in pairs for LVDS can alternatively be used individually for other types of signaling. The LVDS buffers are constructed to give good performance and to meet LVDS specifications despite variations due to temperature, manufacturing process inconsistency, and power supply changes.
摘要:
A circuit provides a programmable phase shift feature, where the phase shift is programmably selectable by a user. This circuitry may be incorporated in a programmable logic device (PLD) or field programmable gate array (FPGA) to provide additional programmability features. The programmable phase shift circuitry may be implemented within a phase locked loop (PLL) or delay locked loop (DLL) circuit.
摘要:
A circuit provides a programmable phase shift feature, where the phase shift is programmably selectable by a user. This circuitry may be incorporated in a programmable logic device (PLD) or field programmable gate array (FPGA) to provide additional programmability features. The programmable phase shift circuitry may be implemented within a phase locked loop (PLL) or delay locked loop (DLL) circuit.
摘要:
Techniques and circuitry are provided to handle high frequency input data. The techniques and circuitry take a high-frequency serial input data stream and covert it into parallel form for handling within the integrated circuit. The circuitry ensures the high frequency data is strobed properly by accounting for skew between the high frequency data input and clock input. In an implementation, multiple clock strobes are generated having the same frequency but different phase. A predetermined series of bits is input to the high frequency input into the circuitry for training. One of the multiple clock strobes is selected based on which one correctly determines the bits in the predetermined input data stream. This clock strobe is selected to strobe the high frequency data input for the integrated circuit. In an embodiment, the high frequency data input is an LVDS input of a programmable logic integrated circuit.
摘要:
Method and circuitry for a frequency synthesizer having wide operating frequency range. The frequency synthesizer uses multiple programmable loadable counters in a phase-locked loop arrangement to generate any combination of clock frequencies based on user programmed values. In a specific embodiment of the invention, the phase-locked loop includes a voltage-controlled oscillator with a built-in programmable phase shift. The present invention further provides a preferred embodiment for a high speed loadable down counter for use in the frequency synthesizer.