摘要:
A programmable device such as a field-programmable gate array (FPGA) has programmable I/O circuitry. In one embodiment, a programmable I/O circuit (PIC) associated with at least first and second pads of the device has an output buffer that is selectively connected to the first and second pads via corresponding first and second transmission gates. The transmission gates enable an outgoing signal from the output buffer to be individually and selectively presented at the pads, while reducing the capacitive loading at each pad when the corresponding transmission gate is open (i.e., when the outgoing signal is not to be presented at that pad).
摘要:
A bank of input/output buffers are configured such that each input buffer in the bank may select from a plurality of voltage references during single-ended operation. Similarly, the pad associated with each input buffer may serve to supply one of the voltage references for other input buffers within the bank.
摘要:
An electronic circuit with programmable terminations includes a circuit block, signal pads coupled to the circuit block, programmable termination circuits each associated with a corresponding one of the signal pads, and a reference circuit operative to generate one or more control signals for application to the programmable termination circuits. A given one of the programmable termination circuits is configurable independently of at least one of the other programmable termination circuits into one of a plurality of termination states. Preferably, the programmable termination circuits are each independently configurable to provide a particular termination resistance and a particular supply terminal connection type for the associated signal pad. The invention is particularly well suited for use in integrated circuit applications, such as, for example, those involving FPGAs, FPSCs and ASICs.
摘要:
In one embodiment of the invention, a programmable level shifter can be selectively configured to operate in either a high-speed mode or a low-power mode. In both modes, the level shifter converts an input signal in one power supply domain into an output signal in another power supply domain. In the high-speed mode, p-type devices are configured as a current-mirror amplifier that provides the level shifter with relatively fast switching speed. In the low-power mode, the same p-type devices are configured as a cross-coupled latch that provides the level shifter with relatively low power consumption. Selectively enabled n-type devices provide the low-power mode with larger effective n-type devices to flip the cross-coupled latch formed by the p-type devices in the low-power mode.
摘要:
In one embodiment, an integrated circuit has configurable application circuitry that operates at any one of multiple available power supply voltages. PT-control circuitry, operating at a PT reference voltage, generates a PT-control signal indicative of variations in process and temperature. Application-control circuitry controls the configuration of the application circuitry based on the selected power supply voltage for the application circuitry and the PT-control signal, where the selected power supply voltage is independent of the PT reference voltage. In one implementation, the application circuitry is an output driver having source and sink driver blocks, where driver-control circuitry controls the configuration of the source driver block based on the selected output-driver power supply voltage, a source PT-control signal, and a selected drive strength, while controlling the configuration of the sink driver block based on the selected output-driver power supply voltage, a sink PT-control signal, and a selected drive strength.
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:
An improved output buffer having a digital output slew control and compensation for manufacturing process variations. Output slewing is accomplished by sequencing digital drive signals to paralleled output transistors. In one embodiment, a pre-driver sequences the drive signals by using the propagation delays of serially coupled digital logic gates to reduce power supply droop and/or ground bounce. The output transistors are turned off substantially simultaneously to avoid undesirable power supply DC current flow when the output buffer changes state. Programmably configuring the number of paralleled transistors that may be turned on at any given time allows a user to compensate for manufacturing process variations and determine the output impedance/drive capacity of the buffer.
摘要:
An integrated circuit having a transistor device and over-voltage protection circuitry. The transistor device is implemented in a technology having a specified operating-voltage range, the transistor device having gate, drain, source, and tub nodes, and the specified operating-voltage range having a specified maximum voltage. The over-voltage protection circuitry is adapted to apply gate and tub voltages to the gate and tub nodes, respectively. If at least one channel voltage applied to at least one of the drain and source nodes exceeds the specified maximum voltage, then the over-voltage protection circuitry controls at least one of the gate voltage and the tub voltage to inhibit one or more adverse effects to the transistor device.
摘要:
A termination scheme for the I/O circuitry of a programmable device, such as a field-programmable gate array (FPGA), has programmable resistors switchably connected between reference voltages and two of the device's I/O pads and additional programmable resistors switchably connected between the two I/O pads. By appropriately controlling the reference voltages and the resistance levels, a single implementation of the termination scheme can be used to conform to a relatively wide variety of symmetric and non-symmetric complementary and differential signaling applications.