Actel Corporation, Inc.

Visic, Inc.

Actel Corporaton

Douglas C Galbraith

Jonathan W Greene

Abbas A El Gamal

Michael G Ahrens

Abdelshafy A Eltoukhy

Esmat Z Hamdy

Steve S Chiang

A logic module includes first and second multiplexers each having two data inputs and a select input. Both select inputs are connected to the output of a two-input logic gate of a first type. The inputs to the first and second multiplexers comprise data signals from a first group. One input of each logic gate comprises a data signal of a second group and the other input of each logic gate comprises a data signal of a third group. A third multiplexer has first and second data inputs connected the outputs of the first and second multiplexers, respectively, and a select input connected to the output of a two-input logic gate of a second type. Its output is connected to a first data input of a fourth multiplexer having a HOLD1 input coupled to its select input. Its output and a CLEAR input are presented to an AND gate whose output is connected to the second data input of the fourth multiplexer and to the first data input of a fifth multiplexer. The fifth multiplexer select input comprises a HOLD2 input. Its output and the CLEAR input are presented to an AND gate whose output is connected to the second data input of the fifth multiplexer and to an output node. The CLEAR, HOLD1 and HOLD2 inputs comprise combinations of signals from a data signal of a third group which may contain data signals of one of the other groups.

Logic module with configurable combinational and sequential blocks

A logic module includes first and second multiplexers each having two data inputs and a select input. Both select inputs are connected to the output of a two-input logic gate of a first type. The inputs to the first and second multiplexers comprise data signals from a first group. One input of each logic gate comprises a data signal of n second group and the other input of each logic gate comprises a data signal of a third group. A third multiplexer has first and second data inputs connected the outputs of the first and second multiplexers, respectively, and a select input connected to the output of a two-input logic gate of a second type. Its output is connected to a first data input of a fourth-multiplexer having a HOLD1 input coupled to its select input. Its output and a CLEAR input are presented to an AND gate whose output is connected to the second data input of the fourth multiplexer and to the first data input of a fifth multiplexer. The fifth multiplexer select input comprises a HOLD2 input. Its output and the CLEAR input ere presented to an AND gate whose output is connected to the second data input of the fifth multiplexer and to an output node. The CLEAR, HOLD1 and HOLD2 inputs comprise combinations of signals from a data signal of a third group which may contain data signals of one of the other groups.

Logic module for a programmable logic device

A logic module includes a first and a second two-input multiplexer each having first and second data inputs. Both the first and second multiplexer include a select input, both of which are connected to the output of a two-input logic gate of a first type having first and second data inputs. The inputs to the first and second two-input multiplexers are sourced with data signals from a first group. One input of each of the logic gates is sourced from a data signal of a second group and the other input of each of the logic gates is sourced from a data signal of a third group. A third two-input multiplexer has its first and second data inputs connected the outputs of the first and second multiplexers, respectively. A select input of the third two-input multiplexer is connected to the output of a two input logic gate of a second type having first and second data inputs. The output of the third two-input multiplexer is connected to a first data input of a fourth two-input multiplexer having a HOLD1 input coupled to its select input. Its output is and a CLEAR input are presented to an AND gate whose output is connected to the second data input of the fourth two-input multiplexer and to the first data input of a fifth two-input multiplexer. The select input of the fifth two-input multiplexer is connected to a HOLD2 input. Its output and the CLEAR input are presented to an AND gate whose output is connected to the second data input of the fifth two-input multiplexer and to an output node. The CLEAR, HOLD1 and HOLD2 inputs are defined by combinations of signals from a data signal of a third group which may contain a data signal of one of the other groups.

A method for simultaneously programming a plurality of antifuses each having a first electrode connected to a common node and each having a second electrode connected to an isolated node electrically isolated from the nodes of each of the other antifuses includes the steps of precharging the common node and the isolated nodes to an intermediate voltage potential selected to minimize the stress on all antifuses; precharging the isolated nodes of selected ones of the antifuses to a first programming voltage potential placing a second programming voltage potential on said common node, the first and second programming voltage potentials selected such that the difference between them is sufficient to cause programming of said antifuses and such that said intermediate potential is substantially centered between them, waiting a predetermined amount of time; and measuring the current flowing between the common node isolated nodes. If the measured current indicates that the desired antifuse has not been programmed the programming process may be attempted a preselected number of times. After the selected antifuses have been programmed, they are individually soaked by passing a soaking current through them.

Simultaneous multiple antifuse programming method

A method for isolating a first low-voltage circuit node comprising an output of a low-voltage device from a second circuit node which carries high programming voltages during programming of user-programmable interconnect elements includes the step of raising the normal power supply voltage provided to the low-voltage devices to an intermediate level lower than the programming voltage but high enough to protect the outputs of the low voltage devices from damage. The output to be protected is caused to assume a desired state and is then inhibited from changing state during the programming cycle. Programming voltage is then applied to the low voltage circuit node.

Methods for protecting outputs of low-voltage circuits from high

A circuit for preventing false programming of unselected anti-fuses in an anti-fuse array includes a series impedance including a plurality of transistors which may be used for partial address selection connected between a source of programming voltage and a bit line.

Circuit for preventing false programming of anti-fuse elements

A semiconductor or substrate of a first conductivity type includes a well structure of a second conductivity type formed therein. A first low voltage MOS transistor includes spaced apart source and drain regions of the first conductivity type in the well. A first transistor gate lies above a channel region which is disposed between the source and drain regions of the first low voltage MOS transistor and is separated therefrom by a gate dielectric having a first thickness. A second high voltage transistor includes spaced apart source and drain regions of the first conductivity type in the well. A second transistor gate lies above a channel region which is disposed between the source and drain regions of the second high voltage transistor and is separated therefrom by a gate dielectric having a second thickness which is greater than the thickness of the gate dielectric of the first low voltage MOS transistor. A first contact diffusion, having the same conductivity type as the well, is located at the edge of the well closest to the first low voltage transistor, and is connected to a source of voltage. A second contact diffusion, having the same conductivity type as the well, is located at the edge of the well closest to the second high voltage transistor, and is also connected to the source of voltage.

Low voltage device in a high voltage substrate

The present invention includes four approaches to reduce the unintended programming of antifuses while programming selected antifuses and to decrease the programming time. The first approach includes circuitry to maintain the voltage placed on unselected antifuses at a constant level by use of a voltage source. According to the second approach, a resistor is included in series with the voltage source. According to the third approach, a diode is included in series with the voltage source. According to the fourth approach, a MOS implementation of a diode is included in series with the voltage source.

Apparatus for improving antifuse programming yield and reducing antifuse

A circuit for isolating a first low-voltage circuit mode from a second circuit node which carries high programming voltages during programming of user-programmable interconnect elements includes a novel two input NAND gate having one input structure configured from high voltage devices connected to the second circuit node. The other input of the NAND gate is a control input for the isolation device and is connected to a low-voltage logic signal which is high when the signal from the high programming voltage node is to be passed through to the low-voltage node and low when the low-voltage node is to be isolated from the high programming voltage node. The output of the NAND gate is connected to the first low-voltage circuit node.

Circuits for preventing breakdown of low-voltage device inputs during

A logic module includes a first and a second two-input multiplexer each having first and second data inputs. Both the first and second multiplexer include a select input, both of which are connected to the output of a two-input logic gate of a first type having first and second data inputs. The inputs to the first and second two-input multiplexers are sourced with data signals from a first group. One input of each of the logic gates is sourced from a data signal of a second group and the other input of each of the logic gates is sourced from a data signal of a third group. A third two-input multiplexer has its first and second data inputs connected the outputs of the first and second multiplexers, respectively. A select input of the third two-input multiplexer is connected to the output of a two-input logic gate of a second type having first and second data inputs. The output of the third two-input multiplexer is connected to a first data input of a fourth two-input multiplexer having a HOLD1 input coupled to its select input. Its output is and a CLEAR input are presented to an AND gate whose output is connected to the second data input of the fourth two-input multiplexer and to the first data input of a fifth two-input multiplexer. The select input of the fifth two-input multiplexer is connected to a HOLD2 input. Its output and the CLEAR input are presented to an AND gate whose output is connected to the second data input of the fifth two-input multiplexer and to an output node. The CLEAR, HOLD1 and HOLD2 inputs are defined by combinations of signals from a data signal of a third group which may contain a data siganl of one of the other groups.

An input/output module circuit for providing input/output interface functions in integrated circuits includes an input section and an output section electrically connected to an I/O pad of the integrated circuit. The input section includes an input buffer/level shifter for translating the logic signals from the outside world to CMOS compatible levels. The input buffer may be placed in a high impedance state by a control signal applied to a control input. The output of the input buffer/level shifter is connected to a first data input of a two-input multiplexer. The output of the two-input multiplexer is connected to an internal bus and to the second data input of the two-input multiplexer. The select input of the two-input multiplexer is connected to a control signal, preferably to the same control signal used to enable the input buffer/level shifter. The output section of the input/output module section of the present invention includes a two-input multiplexer having a first input connected to an internal data bus, and its output fed back to its second data input. Its select input is driven from a control signal. The output of the two-input multiplexer is also connected to the input of an HCT buffer. The output of the HCT buffer is connected to an I/O pad of the integrated circuit, which may be the same pad to which the input section is connected. The slew input of the HCT buffer is driven from a signal enabling slow or fast rise times. The enable input of the HCT buffer is driven from an enable signal which may be derived from other logic signals.

Input/output module with latches

A circuit is provided for switching an internal bus of an integrated circuit between an input/output pad on the integrated circuit and a circuit node of the integrated circuit. A first switch is connected between the input/output pad and the internal bus. A second switch is connected between the circuit node and the internal bus. A high voltage detector senses the presence or absence of a voltage exceeding a preselected threshold on the input-output pad. The high voltage detector assumes a first state if the voltage on the input/output pad exceeds the preselected threshold, and assumes a second state if the voltage on the input/output pad does not exceed the preselected threshold. Switch control circuitry responsive to the high voltage detector activates either the first or second switch depending upon the output of the high voltage detector. Circuitry is provided to prevent the first and second switches from being active simultaneously and for lowering the capacitance of the input/output pad.

Integrated circuit bus switching circuit

A high speed static single ended sense amplifier is disclosed, including, an input node, an output node, a first P-channel input transistor having its source connected to a source of positive voltage, its drain connected to the input node and its gate connected to a feedback node, a first N-channel input transistor having its drain connected to the input node, its source connected to a source of negative voltage and its gate connected to the feedback node, a first output P-channel transistor having its source connected to a source of positive voltage, its drain connected to the output node, and its gate connected to the feedback node, a first N-channel output transistor having its drain connected to the output node, its source connected to a source of positive voltage and its gate connected to the feedback node, an N-channel feedback transistor having its gate connected to the output node, its drain connected to a source of positive voltage and its source connected to the feedback node, a capacitive voltage divider connected between the source of negative voltage, the source of positive voltage, and the input node, the capacitive voltage divider including a parasitic capacitance and a P-channel gate capacitor connected between the input node and one of the positive or negative voltage sources, the capacitance ratio of the capacitive voltage divider being such as to give the same voltage divider ratio as the voltage divider ratio resulting from the first P-channel MOS input transistor and the first N-channel MOS input transistor.

High speed static single-ended sense amplifier

The high-speed static differential sense amplifier of the present invention is composed of two stages. The first stage uses a source follower to feed a set of dual complimentary current mirrors. The current mirrors in the source of the input devices convert the voltage difference supplied by the source follower into a current. This current is mirrored into the second stage by opposing pull-down and pull-up current mirrors from the first stage. The second stage current difference produces the large voltage swings needed to drive the digital logic.

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Fremont, CA, United States of America

Douglas C Galbraith