摘要:
The FPGA has an array of programmable logic cells (PLCs) surrounded by a ring of programmable input/output cells (PICs). In one embodiment, the pads of each pair of adjacent PICs, as well as internal routing resources of each of the two PICs, are programmably connected to a single global-signal spine, and the spine is programmably connected directly to only half of the perpendicular branches. Each of the branches can then connect to the cells in two adjacent rows/columns of the array to provide a global signal to any of the cells in the array while only using a branch per every two rows/columns of the device. The reduced number of spine-to-branch connections reduces the capacitive loading on the spines, thereby increasing the speed at which global signals can be transmitted. In addition, sharing spines between adjacent PICs reduces the number of spines in the FPGA by half, thereby providing additional layout space for other resources. Sharing branches also has the same effect as sharing spines in that the number of branches is reduced by half, also increasing global signal speed. These advantages are achieved without reducing the programming flexibility of the FPGA.
摘要:
The invention provides an input/output (I/O) signaling voltage range discriminator (and corresponding method) which is used to control a configurable logic device such as a configurable I/O buffer in a second electronic circuit in response to a detected signaling voltage range of a first electronic circuit. The discriminator outputs an indication of the signaling voltage range of the first electronic circuit to a configurable I/O buffer enabling it to adapt to the signaling levels used by the first electronic circuit. The I/O buffer, based on the indication provided by the discriminator, can then configure its logic to become tolerant and/or compatible with digital signals transferred to and from the first electronic circuit.
摘要:
A single integrated circuit (IC) having one or more regions of mask-programmed device (MPD) logic for implementing permanent functions and one or more regions of field-programmable gate-array (FPGA) logic for implementing user-specified functions. The FPGA-type logic provides programming flexibility, while the MPD-type logic provides size, speed, functionality, and dollar cost advantages. In one embodiment, a hybrid IC has an array of programmable logic cells (PLCs) implemented using FPGA-type logic, an application-specific block (ASB) implemented using MPD-type logic, and a ring of pads. Fast interface switch hierarchy (FISH) cells provide the interface between the PLC array and the pads, between the PLC array and the ASB, and between the ASB and the pad ring. Muxes in the FISH cells can be programmed to cause the FISH cells to operate either (1) as programmable interface cells (PICs) that provide a direct interface between the PLC array and the pad ring or (2) as ASB-interface cells (AICs) that (a) provide interfaces between the PLC array and the ASB and (b) control interfaces between the ASB and the pad ring.
摘要:
Systems and methods are disclosed to provide static and/or dynamic phase adjustments to a data signal relative to a clock signal. For example, the data signal may be delayed by a coarse delay and/or a fine delay to match the timing of the clock signal independently for each input path (e.g., per input pad). The delay may be as a function of positive and/or negative clock edges.
摘要:
In one embodiment of the invention, a programmable termination structure has first and second termination circuits for corresponding pads and a programmable connection therebetween. The first termination circuit supports first and second sets of termination schemes. A shared resistor is part of at least one termination scheme in each set. The first termination circuit supports a termination scheme between the first pad and a user-defined node connected to an on-chip capacitor such that first pad is connected via the termination scheme to the on-chip capacitor. Control circuitry automatically turns on and off a termination scheme for bidirectional signaling supported by the first termination circuit, wherein (1) the control circuitry turns off the termination scheme if an output buffer is configured to present outgoing signals at the first pad and (2) the control circuitry turns on the termination scheme if the output buffer is disabled in order to terminate incoming signals received at the first pad.
摘要:
A multi-functional programmable I/O buffer in a Field Programmable Gate Array (FPGA) device. The I/O buffer is programmably configurable to meet any of a wide range of I/O standards, be it single ended or differential, 5V, 3.3V, 2.5V or 1.5V logic, without the need for implementing multiple I/O buffers to properly handle each different iteration of I/O requirements. An embedded, internal programmable resistor (e.g., a programmable 100 ohm resistor) is programmably selected for use in differential I/O applications, thus eliminating the conventional requirement for the use of an external resistor connected to each differential receiver I/O pin. The present invention also separates I/O pads into groups in each of a plurality of banks in a programmable device (e.g., PLD, FPGA, etc.), with each group being separately powered by the user. The disclosed multi-functional I/O buffer may be programmably configured by the user to be, e.g., a single ended receiver or transmitter, a reference receiver or transmitter, or a differential receiver or transmitter. The pad logic of the multi-functional I/O buffer may include a double data rate input and output mode, each of which includes two flip-flop devices operating on opposite sides of a data clock signal. One of the two flip-flop devices may be borrowed from another logic element, e.g., from a shift register logic element.
摘要:
A field-programmable gate array (FPGA) having at least one programmable cell (e.g., an input/output (I/O) cell) having an output node circuit (e.g., a pad circuit) in which the output data signal and the tri-state signal are applied to a multiplexer that drives the tri-state port of an output buffer in the output node circuit. This configuration enables the output node circuit to be configured for open drain drive mode operations in a fast, predictable manner that does not need to rely on the FPGA's general routing resources.
摘要:
In one embodiment of the invention, an integrated circuit, such as an FPGA, has one or more programmable termination schemes, each having a plurality of resistive termination legs connected in parallel, and a calibration circuit designed to control each termination scheme for process, voltage, and temperature (PVT) variations. The sense element in the calibration circuit and each resistive leg in each termination scheme has a transistor-based transmission gate connected in series with a non-silicided poly (NSP) resistor. The negative temperature coefficient of resistivity of each NSP resistor offsets the positive temperature coefficient of resistivity of the corresponding transmission gate to provide a temperature-independent sense element and temperature-independent termination legs. The temperature-independence and constant IV characteristic of the sense element and termination legs enable a single calibration circuit to simultaneously control multiple termination schemes operating at different termination voltage levels.
摘要:
In one embodiment, an integrated circuit, such as an FPGA, has one or more programmable termination schemes, each having a plurality of resistive termination legs connected in parallel, and a calibration circuit designed to control each termination scheme for process, voltage, and temperature (PVT) variations. A sense element in the calibration circuit and each resistive leg in each termination scheme has a transistor-based transmission gate connected in series with a non-silicided poly (NSP) resistor. The negative temperature coefficient of resistivity of each NSP resistor offsets the positive temperature coefficient of resistivity of the corresponding transmission gate to provide a temperature-independent sense element and temperature-independent termination legs. The temperature-independence and constant IV characteristic of the sense element and termination legs enable a single calibration circuit to simultaneously control multiple termination schemes operating at different termination voltage levels.
摘要:
In one embodiment of the invention, a bias signal monitor has two signal comparators that compare two (power supply) voltages at two different bias points and a logic circuit that processes the outputs from the two signal monitors to generate a bias signal monitor output signal. The logic circuit implements hysteresis-based processing such that (1) if both signal comparators are active (indicating that a first voltage is greater than the second voltage relative to both bias points), then the monitor output is active, (2) if both signal comparators are inactive (indicating that the first voltage is not greater than the second voltage relative to either bias point), then the monitor output is inactive, and (3) if one signal comparator is active and the other is inactive, then the monitor output keeps its previous value. This hysteresis characteristic prevents relatively small oscillations between the voltages from changing the monitor output.