Abstract: Programmable logic device integrated circuitry having I/O circuitry portions having different maximum speed capabilities and different amounts of programmability for supporting various I/O signaling standards is provided. High-speed I/O circuitry and low-speed I/O circuitry may be provided. The high-speed I/O circuitry may have differential I/O drivers and may not be programmable. Relatively few I/O lines may be connected to the high-speed I/O circuitry. The low-speed I/O circuitry may be programmable so that a user may configure the low-speed I/O circuitry to support different I/O signaling standards. Intermediate-speed I/O circuitry may be provided that is more flexible than the high-speed circuitry and operates at higher maximum I/O data rates than the low-speed I/O circuitry.

Abstract: A technique of fabricating a nonvolatile device includes forming a low doping region to aid in the reduction of substrate hot electrons. The nonvolatile device may be a floating gate device, such as a Flash, EEPROM, or EPROM memory cell. The low doping region has a lower doping concentration than that of the substrate. By reducing substrate hot electrons, this improves the reliability and longevity of the nonvolatile device.

Abstract: A delay cell has selectable numbers of parallel load resistance transistors operable in parallel, and a similarly selectable number of bias current transistors connectable in parallel. The delay cell is preferably differential in construction and operation. A voltage controlled oscillator (“VCO”) includes a plurality of such delay cells connected in a closed loop series. Phase locked loop (“PLL”) circuitry includes such a VCO controlled by phase/frequency detector circuitry. The PLL can have a very wide range of operating frequencies as a result of the ability to control the number of load resistance transistors and bias current transistors that are active or inactive in each delay cell. Such activation/deactivation may be programmable or otherwise controlled.

Abstract: A technique and circuitry interfaces a programmable logic integrated circuit compatible with one voltage level to other integrated circuits compatible with a different voltage level. In particular, an on-chip voltage less than the external supply level of the programmable logic integrated circuit is provided to a core portion of a programmable logic integrated circuit by way of a conversion transistor. In an embodiment, the layout (or physical structure) of the conversion transistor is distributed surrounding the core portion. Externally, the programmable logic integrated circuit will interface with an external supply voltage level. The input and output signals to and from the programmable logic integrated circuit will be compatible with the external supply level.

Abstract: A technique of fabricating a nonvolatile device includes forming a low doping region to aid in the reduction of substrate hot electrons. The nonvolatile device may be a floating gate device, such as a Flash, EEPROM, or EPROM memory cell. The low doping region has a lower doping concentration than that of the substrate. By reducing substrate hot electrons, this improves the reliability and longevity of the nonvolatile device.

Abstract: A delay cell has selectable numbers of parallel load resistance transistors operable in parallel, and a similarly selectable number of bias current transistors connectable in parallel. The delay cell is preferably differential in construction and operation. A voltage controlled oscillator (“VCO”) includes a plurality of such delay cells connected in a closed loop series. Phase locked loop (“PLL”) circuitry includes such a VCO controlled by phase/frequency detector circuitry. The PLL can have a very wide range of operating frequencies as a result of the ability to control the number of load resistance transistors and bias current transistors that are active or inactive in each delay cell. Such activation/deactivation may be programmable or otherwise controlled.

Abstract: A technique of fabricating an integrated circuit adaptable for use in various operating voltage environments. The same integrated circuit design may be used in different operating modes depending on the particular option selected. For example, there may be three options (710, 715, 720). The various options of the integrated circuit formed on the same integrated circuit. During the fabrication of the integrated circuit, the desired option is selected. This may be accomplished, for example, by selecting the appropriate metal masks (725). Other techniques include, to name a few, using programmable links, programmable fuses, programmable cells, and many others. The technique of the present invention reduces the costs of integrated circuits. The same design may be used for a variety of purposes and in a variety of voltage environments without needing to develop and design a specific integrated circuit for each voltage condition.

Abstract: A technique provides an on-chip voltage to a core portion of a programmable logic integrated circuit by way of a conversion transistor. The on-chip voltage may be a reduced internal voltage, less than the VCC of the integrated circuit. In an embodiment, the layout (or physical structure) of the conversion transistor is distributed surrounding the core portion. By providing the core with a reduced voltage, the integrated circuit may interface with other integrated circuits compatible with different voltage levels.

Abstract: An input/output driver for interfacing directly with a voltage at a pad which is above a supply voltage for the input/output driver. This may be referred to as an “overvoltage condition.” For example, if the supply voltage is 3.3 volts, a 5-volt signal may be provided at the pad of the input/output driver. The input/output driver will tolerate this voltage level and prevent leakage current paths. This will improve the performance, reliability, and longevity of the integrated circuit. The input/output driver includes a well-bias generator for preventing leakage current paths.

Abstract: A technique of fabricating a nonvolatile device includes forming a low doping region to aid in the reduction of substrate hot electrons. The nonvolatile device may be a floating gate device, such as a Flash, EEPROM, or EPROM memory cell. The low doping region has a lower doping concentration than that of the substrate. By reducing substrate hot electrons, this improves the reliability and longevity of the nonvolatile device.

Abstract: A programmable logic device architecture. This programmable logic architecture includes a first logic block (425) containing programmable logic elements for performing logic functions. The architecture may also include a diagnostic block interface (415), which interfaces with the first logic block (425), for performing JTAG functions, configuring the first logic block (425), initializing the first logic block (425), interfacing with off-chip diagnostic and test devices and equipment, and performing other similar functions. The first logic block (425) may be programmably coupled to other components on the integrated circuit using a first programmable interconnect network (511). The first logic block (425) includes a plurality of second logic blocks (505) which may be programmably coupled using a second programmable interconnect network (521). The second programmable interconnect network (521) may be programmably coupled to the first programmable interconnect network (511).

Abstract: A technique provides an on-chip voltage to a core portion of an integrated circuit by way of a conversion transistor. The on-chip voltage may be a reduced internal voltage, less than the VCC of the integrated circuit. In an embodiment, the layout (or physical structure) of the conversion transistor is distributed surrounding the core portion. By providing the core with a reduced voltage, the integrated circuit may interface with other integrated circuits compatible with different voltage levels.

Abstract: An integrated circuit has one or more external control pins to control and indicate which of two or more different VCC or other voltage levels will be used. The control pin receives a logic signal, high or low, and draws zero static power. A user can use the integrated circuit with two or more VCC voltage levels by indicating which voltage level at the control pins. In a specific embodiment, the integrated circuit has nonvolatile memory cells such as EEPROM or Flash cells that a configurable and reconfigurable using on-chip programming circuitry. The programming circuitry may generate and use superhigh or high voltages, higher than the VCC voltage.

Abstract: A programmable logic device has embedded random access memory (“RAM”) that can function equally well in either single-port or dual-port operation. The RAM is dual-port RAM whose read address inputs and write address inputs are both connected to a conductor bus via two different sparsely populated programmable interconnection resources. The programmable interconnection resources are arranged so that each pair of corresponding read address and write address inputs can be connected to at least one conductor in common on the conductor bus, allowing the RAM to be configured to mimic a single-port RAM as read address signals and write address signals originating at remote components of the programmable logic device “think” they are being directed to the same address inputs.

Abstract: An input/output driver for interfacing directly with a voltage at a pad (820) which is above a supply voltage (817) for the input/output driver. This may be referred to as an “overvoltage condition.” For example, if the supply voltage is 3.3 volts, a 5-volt signal may be provided at the pad of the input/output driver. The input/output driver will tolerate this voltage level and prevent leakage current paths. This will improve the performance, reliability, and longevity of the integrated circuit. The input/output driver includes a well-bias generator (1002) for preventing leakage current paths.

Abstract: A technique provides an on-chip voltage to a core portion of an integrated circuit by way of a conversion transistor. The on-chip voltage may be a reduced internal voltage, less than the VCC of the integrated circuit. In an embodiment, the layout (or physical structure) of the conversion transistor is distributed surrounding the core portion. By providing the core with a reduced voltage, the integrated circuit may interface with other integrated circuits compatible with different voltage levels.

Abstract: Methods and apparatus for initializing and determining the contents of a memory block in a programmable logic device. One apparatus includes a logic element, programmably configurable to implement user-defined combinatorial or registered logic functions, and a memory block to store data. The memory block is coupled to the logic element. The memory block includes a memory storage cell to store a first data bit, a shadow cell to store a second data bit, and a transfer circuit. When a first control line of a transfer circuit is asserted, the second bit is transferred from the shadow cell to the memory storage cell. When a second control line of the transfer circuit is asserted, the first bit is transferred from the memory storage cell to the shadow cell.

Abstract: A technique and circuitry to interface an integrated circuit to other integrated circuits in a mixed-voltage mode environment. In particular, the integrated circuit is fabricated using technology compatible with an internal supply voltage level. Externally, the integrated circuit will interface with an external supply voltage level, above the internal supply voltage level. The input and output signals to and from the integrated circuit will be compatible with the external supply level. Specifically, a level shifter (1317) or similar conversion circuit is used to convert voltages compatible with the internal supply level to be compatible with the external supply level.

Abstract: A technique and circuitry to interface an integrated circuit to other integrated circuits in a mixed-voltage mode environment. In particular, the integrated circuit is fabricated using technology compatible with an internal supply voltage level. Externally, the integrated circuit will interface with an external supply voltage level, above the internal supply voltage level. The input and output signals to and from the integrated circuit will be compatible with the external supply level. Specifically, a level shifter (1317) or similar conversion circuit is used to convert voltages compatible with the internal supply level to be compatible with the external supply level.

Abstract: An integrated circuit for implementing reconfigurable logic, such as a field programmable gate array (“FPGA”), as described herein has multiple blocks of multiported memory. The memory has a plurality of read ports and a plurality of write ports. Each port of the multiported memory can be configured with a width and depth that is independent and separate from the width and depth of the other ports. The memory also includes a port for taking a synchronous snapshot of the contents of the memory or for loading the memory to an initial state. The memory shares routing lines used by a low level logic element thereby alleviating the need to add routing lines to an interconnect network just to satisfy the memory requirements.