摘要:
A programmable device with logic blocks is configured to cascade product terms from one logic block to another to increase the logical input width of the product terms. Each logic block may produce a plurality of product terms based upon the selection of inputs from a routing structure. Logic blocks configured to receive cascaded product terms includes a plurality of AND gates corresponding to the plurality of product terms.
摘要:
Circuitry is provided for testing fusible link arrays for short circuits around the fusible links. Each link is electrically isolated and compared with a pair of reference fusible links to detect the presence or absence of a short circuit.
摘要:
A unique double inversion buffer has a first means to invert and isolate the digital input signal, a second means to reinvert and further isolate the input signal, and an output means including an output transistor 94. The double inversion buffer is configured with active pull-down means on the output transistor 92. The high-to-low propagation delay time and the low-to-high propagation delay times through the double inversion buffer and reduced by use of the active pull-down means. Rapid turnoff of the output transistor is accomplished by coupling a transistor to its base to instantaneously turn it off. In a preferred embodiment, a clamping circuit 201 is used to hold the output voltage at a maximum predetermined level to further reduce the time it takes to reduce the output voltage to the logical "0" state.
摘要:
Test circuitry is included in a PROM memory for detecting shorts between bit lines and word lines and shorts or leaks in a memory cell. The circuitry enables a selected positive voltage to be applied across all memory cells in the memory so that the existence of leaky memory cells or shorts in the memory can be detected during testing. The test circuitry has no appreciable effect on the memory during normal operation of the memory.
摘要:
Test circuitry is included in a PROM memory for detecting shorts between bit lines and word lines and shorts or leaks in a memory cell. The circuitry enables a selected positive voltage to be applied across all memory cells in the memory so that the existance of leaky memory cells or shorts in the memory can be detected during testing. The test circuitry has no appreciable effect on the memory during normal operation of the memory.
摘要:
An output circuit (50) is provided for a programmable logic array (PLA) integrated circuit. The output circuit (50) includes a flip flop (52) which stores a given output term from the array. The flip flop (52) contains a set input lead (S) and a reset input lead (R). The signals present at the set input, reset input, the clock leads are generated by programmable logic within the PLA. A multiplexer (54) is provided which receives the output data of the flip flop (52) and the signal constituting the input data for the flip flop. The multiplexer provides the data input signal on the multiplexer output lead (60) when both the set and reset input signals are true. However, if either or both the set and reset input signals are false, then the multiplexer (54) provides the Q output signal from the flip flop (52) on the multiplexer output lead (60). The multiplexer output signal is presented to a three-state buffer (62) which in turn drives an output pin.
摘要:
Means are provided for replacing a defective row (or column) of memory in a fuse-array PROM which comprises disabling the defective row and programming a redundant row to respond to the address of the defective row. Means are also provided for reducing the swing between high and low address voltages.The redundant row is connected via an AND gate through fuses to all ADDRESS and ADDRESS lines of the address buffer, so that the redundant row is always off until programmed. If a defective row is found, all memory cells in the defective row are disabled and the redundant row is programmed by selectively blowing fuses leading to the ADDRESS and ADDRESS lines thus causing the redundant row to respond to the address of the defective row.
摘要:
An improved programmable logic device includes a set of I/O cells, a set of logic blocks, and a routing pool that provides connections among the logic blocks and the I/O cells. At least one of the logic blocks includes a programmable logic array that generates product term output signals on product term output lines. A first product term summing circuit has input terminals, at least one of which is coupled to a product term output line. The first product term summing circuit generates an output signal at an output terminal in response to at least one product term output signal. Likewise, a second product term summing circuit has input terminals, at least one of which is coupled to a product term output line. The second product term summing circuit generates an output signal at an output terminal in response to at least one product term output signal. The logic block further includes first and second output lines and a first programmable switching device that programmably couples the first output line to the output terminal of either the first or the second product term summing circuit. The logic block further includes a second programmable switching device that programmably couples the second output line to the output terminal of either the first or the second product term summing circuit. The programmable logic device has increased functional capacity. In addition, generating an interconnect solution to program the programmable logic device is made simpler by the present invention.
摘要:
A circuit for providing programmable voltage output levels in a logic device includes a pull-up device for driving an output pad with either a first voltage output level or a second voltage output level. A charge pump generates a pumped voltage. A first clamp regulator, coupled to the charge pump and the pull-up device, receives a first reference signal. The first clamp regulator, in response to the first reference signal, generates a first voltage from which the first voltage output level is derived. A second clamp regulator, coupled to the pull-up device, receives a second reference signal. In response to the second reference signal, the second clamp regulator generates a second voltage from which the second voltage output level is derived. A passgate multiplexer is coupled to the first and second clamp regulators. The passgate multiplexer receives at least one output voltage select signal. In response to the at least one output voltage select signal the passgate multiplexer selects either the first voltage output level or the second voltage output level.
摘要:
A programmable integrated circuit device includes a plurality of output terminals, each output terminal for use in transmitting a respective output signal. Timing control circuitry is connected to the output terminals. The timing control circuitry is operable to delay the output signal on each output terminal and is further operable to control a slew rate of the output signal on each output terminal.