Abstract: An on-chip mode-setting circuit and method are provided for a chip having an output driver with an output terminal connected to a pin of the chip. The pin may be defined between two states from exterior of the chip. The on-chip mode-setting circuit includes an electronic element connected to a bias input of the output driver for producing a voltage when the pin is defined at one of the two states, and a voltage detector for monitoring the voltage to determine which one of the two states the pin is at, and producing a mode-setting signal accordingly.

Abstract: Clamp networks are provided to insure successful operation of a variety of electronic circuits that are realized in the form of integrated circuit chips. These networks are especially suited for use in chips in which on-chip circuits generate a voltage to bias the chip substrate relative to the chip ground. The clamp networks are configured to drive a current between the chip ground and the chip substrate whenever the chip substrate begins to rise above the chip ground during turn on of the chip input voltage. The clamp networks thus insure that the chip substrate is properly biased when the input voltage has been established and that the chip, therefore, functions as intended.

Abstract: A reference voltage generating circuit includes a current generating section, a voltage generating section, a voltage dividing circuit, and a synthesis section. The current generating section generates a first current having a positive temperature coefficient. The voltage generating section generates a voltage having a negative temperature coefficient. The voltage dividing circuit divides the voltage of the negative temperature coefficient, generated by the voltage generating section. The synthesis section generates a voltage which is the sum of a terminal voltage obtained on causing the first current through a resistor and a voltage obtained on dividing the voltage having the negative temperature coefficient by the voltage dividing circuit, and outputs the sum voltage generated as a reference voltage.

Abstract: Circuits, methods, and apparatus for limiting voltages received by devices in input/output cells to less than the device's breakdown voltage. An exemplary embodiment of the present invention provides an input/output cell having one or more clamp diodes and resistors configured to limit voltages seen by the gates of the devices in the input/output cell. In one embodiment, the clamp diodes are on-chip, while the resistors are off-chip. In a specific embodiment, the clamp diode is connected between an input pad for the input output cell and a supply voltage VCC, while a resistor is off-chip and in series with the input pad. In another specific embodiment, a series of clamp diodes are coupled between ground and an input pad, while a resistor is off-chip and in series with the input pad. In another embodiment, the clamp diode or diodes may be programmably or selectively disconnected. These clamp diodes may be disabled to protect against latch-up.

Abstract: A low power method and apparatus for selecting operational modes of a circuit. One circuit according to the teachings of the disclosed method and apparatus includes a first current limiting circuit coupled between a selector terminal and a first voltage bus. The first current limiting circuit is adapted to vary a current limit out of the selector terminal in response to a voltage on the selector terminal. The circuit also includes a second current limiting circuit coupled between the selector terminal and a second voltage bus. The second current limiting circuit adapted to vary a current limit into the selector terminal in response to the voltage on the selector terminal.

Abstract: An active over-voltage clamp system includes at least one over-voltage detector that is responsive to an input voltage and provides a first current. The system also includes a replica over-voltage circuit that provides a second current, and circuitry subtracting the second current from the first current to produce a difference current. The system further includes a differential clamp activated in response to the difference current. The differential clamp prevents the input voltage from increasing beyond a target voltage.

Abstract: A low power method and apparatus for selecting operational modes of a circuit. One circuit according to the teachings of the disclosed method and apparatus includes a first current limiting circuit coupled between a selector terminal and a first voltage bus. The first current limiting circuit is adapted to vary a current limit out of the selector terminal in response to a voltage on the selector terminal. The circuit also includes a second current limiting circuit coupled between the selector terminal and a second voltage bus. The second current limiting circuit adapted to vary a current limit into the selector terminal in response to the voltage on the selector terminal.

Abstract: A transconductor to convert an input voltage to an output current, includes: a primary transconductance stage to provide the output current from the input voltage and a driving current; an adaptive transconductance stage coupled in series with the primary transconductance stage to generate the driving current from the input voltage; and a bias circuit coupled to provide a primary bias voltage to the primary transconductance stage and an adaptive bias voltage to the adaptive transconductance stage.

Abstract: An input buffer has a high voltage leg in parallel with a low voltage leg. The low voltage leg pulls up the pad when the pad voltage is below the power supply voltage. The high voltage leg remains off when the pad voltage is below the power supply. The low voltage leg is turned off when the pad voltage is above the power supply voltage. The high voltage leg is on when the pad voltage is above power supply voltage. A low voltage bias circuit and a high voltage bias circuit protect the transistors in the low and voltage legs when the pad voltage is above the power supply voltage. As a result, the pull-up circuit is high voltage tolerant and does not sink the current from pad.

Abstract: A circuit adjustable after packaging includes a functional circuit supplied with a power potential and a reference potential and has at least one parameter adjustable by programming at least one programmable element and a circuit to program the programmable element of the functional circuit. The adjustable circuit also includes a limiter circuit to limit the voltage between the power supply potential and the reference potential to an adjustable limiting voltage, and a circuit to adjust the limiting voltage. After adjusting a parameter of the functional circuit, the limiting voltage of the limiter circuit is adjusted.

Abstract: An auto-nulled bandgap reference system employing a substrate bandgap reference circuit with primary and auxiliary amplifiers and a switching circuit which in a first mode develops a voltage to null the offset and noise errors of the auxiliary amplifier and then in the second mode uses the nulled auxiliary amplifier to develop a voltage to null the offset and noise errors of the primary amplifier; and a strobe circuit including an output storage device and a strobe control circuit for periodically powering up a bandgap reference circuit to charge the output storage device and powering down the bandgap reference circuit to conserve power.

Abstract: Methods, systems and thermal sensing apparatus are provided that use bandgap voltage reference generators that do not use trimming circuitry. Further, circuits, systems, and methods in accordance with the present invention are provided that do not use large amounts of chip real estate and do not require a separate thermal sensing element.

Abstract: In a voltage clamp circuit, a normally-on type field-effect transistor having a negative threshold voltage has a drain connected to an input node, a source connected to an output node and grounded via a resistance element, and a gate supplied with an output voltage of a variable direct-current power supply. When a voltage at the output node becomes higher than a clamping voltage because of voltage drop of the resistance element, the field-effect transistor is tuned off. Accordingly, the output voltage is limited to be at most the clamping voltage. Thus, a response speed is higher than those of conventional voltage clamp circuits using diodes or the like.

Abstract: Methods and circuits are disclosed for protecting an electronic circuit from ESD damage using an SCR ESD cell. An SCR circuit is coupled to a terminal of an associated microelectronic circuit for which ESD protection is desired. The SCR used in the ESD cell of the invention is provided with a full guardring for shielding the SCR from triggering by fast transients. A resistor is provided at the guardring for use in triggering the SCR at the onset of an ESD event. Exemplary preferred embodiments of the invention are disclosed with silicide-block resistors within the range of about 2-1000 Ohms or less.

Abstract: The present invention discloses a voltage adjusting circuit including a first switch element, a second switch element, a third switch element, a fourth switch element, a fifth switch element, and a sixth switch element. At first, the voltage adjusting circuit performs a discharging operation on an output voltage toward a reference voltage source, and then when the output voltage level is approaching a voltage level of an input voltage source, the voltage adjusting circuit will perform the discharging operation on the output voltage toward the input voltage source instead, and thus the voltage adjusting circuit can avoid affecting the input voltage source when performing the discharging operation. In addition, the voltage adjusting circuit does not need a digital counter to perform the above dual-phase type discharging operation or multi-phase type discharging operation, and therefore cost of the voltage adjusting circuit is lower, and the voltage adjusting circuit has good accuracy.

Abstract: Protecting elements are respectively connected between a control terminal Ctl and a ground terminal GND of a logic circuit L, between a point Cp and a ground terminal GND, and between a power supply terminal VDD and a ground terminal GND thereof. With this, an E-FET, constituting an inverter 70, and capacitors Ci and Cr can be protected from electrostatic breakdown due to external static electricity. Since the protecting element can be constituted by requisite components for the logic circuit, an additional step or structure is not especially required to provide the protecting element.

Abstract: A pull-up device coupled between an input/output (I/O) pad and a core circuit and has a static pull-up circuit, an adjustment unit, and a control circuit. The static pull-up circuit is coupled to the core circuit and receives a supply voltage. The adjustment unit is coupled to the I/O pad and generates an adjustment signal according to an input voltage of the I/O pad. The control circuit is coupled to the adjustment unit and the static pull-up circuit and controls the static pull-up circuit according to the adjustment signal.

Abstract: In a clamp circuit device, reference voltages are set up by a series circuit of an FET, a resistor and an FET. Gate potentials of FETs are set up by performing addition and subtraction of these reference voltages and a reference voltage generated by a bandgap reference circuit, respectively. The clamp circuit device is constructed by connecting together a source of the one FET with its drain connected with the power supply and a source of the other FET with its drain connected with the ground to an input terminal of a control IC unit. Thus, an input voltage is clamped to [V4+Vtp] when an excessive voltage of positive polarity is applied to an input terminal, and the input voltage is clamped to [V5?Vtn] when an excessive voltage of negative polarity is applied.

Abstract: For supplying voltage to at least one main current consuming unit, a voltage supply unit provides the voltage to the at least one main current consuming unit at a supply node. In addition, an auxiliary current consuming unit conducts auxiliary current from/to the supply node for at least a predetermined time period before the at least one main current consuming unit begins to conduct current. Thus, voltage overshoot is prevented at the supply node.

Abstract: An input buffer has a high voltage leg in parallel with a low voltage leg. The low voltage leg pulls up the pad when the pad voltage is below the power supply voltage. The high voltage leg remains off when the pad voltage is below the power supply. The low voltage leg is turned off when the pad voltage is above the power supply voltage. The high voltage leg is on when the pad voltage is above power supply voltage. A low voltage bias circuit and a high voltage bias circuit protect the transistors in the low and voltage legs when the pad voltage is above the power supply voltage. As a result, the pull-up circuit is high voltage tolerant and does not sink the current from pad.

Abstract: A voltage clamping circuit comprises a first high current gain circuit adapted to receive current from the first line; and a first switching circuit that turns on the first high current gain circuit to flow current away from the first line when the first switching circuit senses a first voltage from the first line above a clamping voltage, and turns off the first high current gain circuit when the first switching circuit senses the first voltage below the clamping voltage.

Abstract: A low power method and apparatus for selecting operational modes of a circuit. One circuit according to the teachings of the disclosed method and apparatus includes a first current limiting circuit coupled between a selector terminal and a first voltage bus. The first current limiting circuit is adapted to vary a current limit out of the selector terminal in response to a voltage on the selector terminal. The circuit also includes a second current limiting circuit coupled between the selector terminal and a second voltage bus. The second current limiting circuit adapted to vary a current limit into the selector terminal in response to the voltage on the selector terminal.

Abstract: An active diode including a NMOS transistor having a source terminal, a drain terminal, a gate terminal and a back gate terminal, where the source terminal is connected to the back gate terminal and forms the anode terminal of the active diode, and the drain terminal forms the cathode terminal of the active diode. The active diode further includes an offset bias voltage source having a first terminal and a second terminal; and an amplifier having a non-inverting input terminal and an inverting input terminal, and an output terminal, where the inverting input terminal is connected to the drain terminal of the transistor, the non-inverting input terminal is connected to the first terminal of the offset bias source, the output terminal is connected to the gate terminal of the transistor, and the second terminal of the offset bias source is connected to the source terminal of the transistor.

Abstract: A method of providing bias voltages for input output connections on low voltage integrated circuits. As integrated circuit voltages drop generally so does the external voltages that those circuits can handle. By placing input and output devices, in series, external voltages can be divided between the devices thereby reducing junction voltages seen by internal devices. By using external voltages as part of a biasing scheme for integrated circuit devices, stress created by the differential between external voltages and internal voltages can be minimized. Additionally device wells can be biased so that they are at a potential that is dependant on the external voltages seen by the low voltage integrated circuit.

Abstract: An input stage includes a signal input (IN) for receiving an input signal s(t) and a digital input stage (15) designed for operation at a supply voltage (VDD). The input stage (15) includes CMOS transistors, which are sensitive to voltages across transistor nodes going beyond a voltage limit (Vmax) and an input (IINV). Voltage limiting circuitry (B) is arranged between the signal input (IN) and the input (IINV). The voltage limiting circuitry (B) includes an input switch (ns) controllable by the state of the input signal s(t), and limit voltages at the input (IINV) to the supply voltage (VDD). In addition, over-voltage protection (A) is provided between the signal input (IN) and the supply voltage (VDD). The circuitry for over-voltage protection (A) includes at least one active circuit element arranged so as to mimic part of a zener function.

Abstract: The clamp circuit of the present invention comprises a low voltage, thin oxide MOS transistor and a trigger element comprising a timing element and at least one inverter. The source and drain of the MOS transistor are connected between a first node and a second node. The timing element comprises a capacitive element and a resistive element connected between the first and second nodes. The inverter is connected between a third node between the capacitive element and the resistive element and the gate of the MOS transistor. Advantageously, one or both of the capacitive element and the resistive element is also implemented in low voltage, thin oxide MOS transistors.

Abstract: Current consumption of an input unit with respect to a bonding option pad is reduced, and erroneous operation of a circuit connected to this bonding option pad is prevented. A boundary scan test circuit is selectively set to an operable or disabled state by a control gate according to a signal from a function set circuit that sets the operation mode according to a potential of a bonding pad. By particularly controlling the operable and disabled state of an input circuit located at the first stage of the test circuit, power consumption can be reduced and erroneous operation while the test circuit is disabled is prevented.

Abstract: The invention is aimed at providing a novel semi-conductor component, as well as a novel process for reading test data. There is a process for reading test data is made available, including reading test data generated during a semi-conductor component test procedure from at least one test data register of a semi-conductor component, storing the test data in at least one useful data memory cell provided on the semi-conductor component, and reading the test data from the at least one useful data memory cell.

Abstract: A power-rail ESD clamp circuit for mixed-voltage I/O buffer is proposed. The power-rail ESD clamp circuit comprises an ESD detection circuit and an ESD protection device. Under normal operating condition, the ESD detection circuit will not trigger the ESD protection device, and therefore the component used in the circuit will not have the gate-oxide reliability issue and also will not generate undesirable leakage current. Under ESD-zapping conditions, the ESD detection circuit will provide some trigger voltage or current to bias the ESD protection device. The ESD protection device can be triggered on quickly to discharge the ESD energy efficiently.

Abstract: Disclosed is a high voltage decoupling capacitor-biasing circuit with no dc current. In one embodiment, the circuit includes a power supply node, a ground node, a common node, a first p-channel FET, a first n-channel FET, and a common node biasing circuit. The first p-channel FET includes a source, gate, and drain, wherein the source and drain of the first p-channel FET are coupled to the power supply node, and wherein the gate of the first p-channel FET is coupled to the common node. The first n-channel FET includes a source, gate, and drain, wherein the source and drain of the first n-channel FET are coupled to the ground node, and wherein the gate of the first n-channel FET is coupled to the common node. The common node biasing circuit is coupled between the power supply and ground nodes. The common node biasing circuit is configured to maintain the common node at a predetermined voltage above ground by charging up or charging down the common node.

Abstract: A voltage clamp circuit is disclosed and claimed. The voltage clamp circuit includes a bypass device and a differential sense amplifier or comparator adapted to control operation of the bypass device. The bypass device is activated in response to the differential sense amplifier or comparator sensing a voltage above a predetermined level.

Abstract: Low voltage drop ORing circuits with zero recovery time and reverse current protection. In use, a MOSFET is coupled between a power supply and a load in a multiple power supply, single load system, or between a power supply and a load in a single power supply, multiple load system, or in both locations in multiple power supply, multiple load systems. A controller senses the current through the MOSFET, and turns the MOSFET off when the current falls below a predetermined threshold current. This allows time for circuit delays and the discharge of the gate of the MOSFET to turn the MOSFET off before the current through the MOSFET car reverse. Turn-on of the MOSFET when the current exceeds the threshold may be purposely slowed to avoid current spikes. Addition of another MOSFET controlled by the controller adds a hot swap capability and the control of the VC slew rate.

Abstract: DC voltage VREF produced in an LSI and having a value between power supply voltage VDD and the ground potential is applied to the gate electrode of pMOS transistor QP1 which forms a function determination circuit. Since the gate voltage of a transistor QP1 is lower than that in a conventional function determination circuit, current through the transistor QP1 is reduced. Hence, the gate length of the transistor QP1 can be reduced. When a second pMOS transistor is connected in parallel to the transistor QP1 so that the transistor has a function for supplying charge to junction A when power is fed to the LSI, the area of the transistor QP1 can be further reduced. When a voltage produced for a purpose other than for the function determination circuit such as a step-down power supply of the LSI is used as DC voltage, the area of the transistor can be reduced.

Abstract: A method of providing bias voltages for input output connections on low voltage integrated circuits. As integrated circuit voltages drop generally so does the external voltages that those circuits can handle. By placing input and output devices, in series, external voltages can be divided between the devices thereby reducing junction voltages seen by internal devices. By using external voltages as part of a biasing scheme for integrated circuit devices, stress created by the differential between external voltages and internal voltages can be minimized. Additionally device wells can be biased so that they are at a potential that is dependent on the external voltages seen by the low voltage integrated circuit.

Abstract: Low noise bandgap references of the type providing a temperature independent output by balancing the proportional to absolute temperature dependence of the difference in base-emitter voltages of two transistors operating at different current densities with the negative temperature coefficient of the base-emitter voltage of a transistor. The bandgap references disclosed reduce the noise characteristic of such references by balancing the difference in base-emitter voltages of a first number of pairs of transistors, each pair having two transistors operating at different current densities, with the negative temperature coefficient of the base-emitter voltage of a second number of transistors, the second number being less than the first number. Various embodiments are disclosed, including embodiments having an output corresponding to the bandgap of the transistor material, and multiples of the bandgap of the transistor material.

Abstract: A system and method are disclosed to help protect a node of associated circuitry from overshooting or undershooting, such as can be associated with power up or other transitional modes. The protection is implemented by diode connecting a transistor, which has its base electrically coupled to the node during the transitional mode. Either after a predetermined time period or after the voltage at the node has reached a desired level, the diode connection can be removed to permit normal operation to begin in which a bias can be provided to the node.

Abstract: A substrate pump circuit and method for I/O ESD protection including NMOS fingers connected to the interconnection between an I/O pad and an internal circuit comprises a MOS device connected to the interconnection between the I/O pad and the internal circuit and the substrate under the control of a switch to turn it on to conduct a pumping current through the substrate resistor when the I/O pad is under ESD stress, so as to pull up the potential of the substrate adjacent to the NMOS fingers, resulting in the reduction of the triggering voltage of the NMOS fingers.

Abstract: A circuit and a method for limiting a voltage to a specified value (e.g., a rail voltage) without clipping thereby includes a pair of MOSFETs that turn on when a specified bias voltage is reached to either add to or sink current from the input node of the resistive load responsive to fluctuations in current going through the output resistive load to maintain a constant current through it. A plurality of biasing circuits is provided that control the turn on voltage levels for the MOSFETs to achieve the desired operation. The biasing circuits include circuit components that are matched to circuit components within the circuitry that adds and drains current to the output resistive load including a resistive load that matches the output resistive load.

Abstract: Charge accumulated at an output node of an output transistor is discharged to the ground through the output transistor as a spike current. To reduce noise of the spike current, a control signal is sent from an output transistor driving circuit set to a low impedance to the output transistor in a first driving stage to quickly turn on the output transistor, a control signal is sent from the output transistor driving circuit set to a high impedance to the output transistor in a second driving stage to output the spike current through the output transistor at a fixed rate, and a control signal is sent from the output transistor driving circuit set to a low impedance to the output transistor in a third driving stage to quickly discharge all the charge. Therefore, a time-current characteristic of the spike current is set almost in a trapezoid shape, and both a spike current peak value and a spike current occurrence time period in the spike current can be sufficiently lowered.

Abstract: The invention relates to a triode type cathode structure comprising a cathode assembly composed of a cathode electrode (33), a layer of electron emitting material (34) and a resistive layer (36) inserted between the cathode electrode (33) and the layer of electron emitting material (34) to connect them together electrically, the structure also comprising a grid electrode (35) separated from the said cathode assembly by a layer of electrical insulation (31). The cathode electrode (33) and the layer of electron emitting material (34) are arranged one at the side of the other.

Abstract: An indirect current sensing circuit and method for replicating an output current is disclosed. The present invention is capable of preventing device damage and circuit disruption by maintaining output voltage signal integrity and consuming negligible power as well as optimizing output impedance. Furthermore, the indirect current sensing circuit and method is independent of semiconductor process variations and thus is more reliable over prior art current sensing techniques. The indirect current sensing circuit and its method of current limiting and output impedance optimization, according to the present invention, can reliably drive transmission lines in networking system and communication applications.

Abstract: An ESD protection circuit utilizes a trigger network to allow the user to select the breakdown voltage of an avalanche transistor. By implementing the trigger network as a string of diodes coupled between the collector and base of the avalanche transistor, the trigger voltage can be programmed between BVCEO and BVCBO by adjusting the number of diodes. When the voltage across the trigger network reaches a predetermined value at which the diodes are conducting under forward biased conditions, but the transistor is below BVCBO, base charge supplied to the transistor caused the transistor to avalanche. A base-emitter resistor prevents false triggering by removing leakage charge from the base of the transistor, and another resistor coupled in series with the base of the transistor limits the removal of charge, thereby causing the avalanche to be self-sustaining once initiated by the trigger network.

Abstract: An output current limiter circuit is effectively insensitive to variations in temperature. A first arm of each of an NPN and a PNP network has a first auxiliary resistor, the current through which is proportional to temperature, and compensates for the negative temperature coefficient of the base-emitter voltage of that arm's (NPN or PNP) transistor, as well as tracks the positive temperature variation in the Vbe-bias control resistor in the other arm of the network. The other arm includes a second additional resistor, the voltage across which is established by a (fixed) bandgap voltage device, that uses a current from which the current through the first arm of the network is derived.

Abstract: A system embodiment for controlling an electrical signal level has a first and a second switch, with one of the switches connected to a high voltage source and the other connected to a low voltage source. One of the switches is biased to an on position when the voltage is less than the low level, with the signal increasing to a level of at least the low level while the switch is biased to the on position. The other of the switches is biased to an on position when the signal is greater than the high level, with the signal discharging to at least below the high level while the switch is in the on position.

Abstract: A bus switch is protected from undershoots on either of its terminals. The bus switch transistor is an n-channel metal-oxide-semiconductor (MOS) with its source connected to a first bus and its drain connected to a second bus. During isolation, the gate node of the bus switch transistor is discharged to ground by a pulsed transistor, and then kept at ground by a leaker transistor. Sense-pulse circuits are attached to the first and second bus. When a low-going transition is detected by a sense-pulse circuit, an n-channel connecting transistor is turned on, connecting the bus with the low-going transition to the gate node through a grounded-gate n-channel transistor. If an undershoot occurs, it is coupled to the gate node. Since both the gate and source of the bus switch transistor are coupled to the undershoot, the gate-to-source voltage never reaches the transistor threshold and the bus switch transistor remains off.

Abstract: An ESD protection circuit that can be easily configured to provide ESD event protection against a range of ESD event voltages. The circuit is also compatible with high frequency ICs. The ESD protection circuit includes an input terminal configured to receive an ESD event signal and a diode sub-circuit. The diode sub-circuit includes at least one diode (e.g., either a single diode or a plurality of diodes connected in series or parallel configuration), a diode input node and a diode output node. The diode sub-circuit is configured to receive an ESD event signal from the input terminal and to operate under forward bias conditions to provide a diode output signal at the diode output node. The circuit also includes a bipolar junction transistor (e.g., a Si—Ge bipolar junction transistor) with a base, a collector and an emitter. The emitter is configured to receive the ESD event signal from the input terminal, while the base is configured to receive the diode output signal from the diode output node.

Abstract: In a programmable integrated circuit, a discharge circuit for discharging high voltage nodes provides a current path whose current is limited by a control voltage. In one embodiment, the current path is implemented by a transistor coupled to the high voltage nodes, with the control voltage provided by a current mirror coupled to the current path. The control voltage is applied across the gate and source terminals of the transistor. In one embodiment, the source terminal of the transistor is precharged to a supply voltage less a threshold voltage of a transistor. With the current in the current path thus limited, threshold voltage shifts and other damages to the functional circuit of the integrated circuit due to the discharge current of high voltage nodes are avoided.

Abstract: A circuit includes an output driver, where the output driver includes a pull-up device and a pull-down device. The pull-up device has a first control terminal that is responsive to an RC-timer so as to bias the pull-up device on in response to an electrostatic discharge (ESD) event that activates a device coupled to an output of the RC-timer. The pull-down device has a second control terminal that, for one aspect, is in a substantially indeterminate state (i.e. the second control terminal may be a “1”, “0” or some other voltage, which may or may not be within the voltage range between “1” and “0”) during the ESD event.

Abstract: A high-voltage tolerance input buffer and a high-voltage ESD protection circuit connected to a pad of an integrated circuit for preventing rapid gate oxide aging. The high-voltage tolerance input buffer of the present invention comprises a voltage-sharing circuit and a switch circuit, wherein the voltage-sharing circuit is connected between the pad and a power rail and generates a reference voltage not higher than the voltage of the pad. The switch circuit is connected to the voltage-sharing circuit and comprises a control gate to control the switching operation of the switch circuit according to the reference voltage. The present invention can be implemented to solve the rapid gate oxide aging problem without incurring any change in the original process flow by employing a voltage-sharing circuit.

Abstract: A dual-node capacitor coupling technique is used to lower the trigger voltage and to improve the uniform turn-on of a multi-finger MOSFET transistor. Preferably, each MOSFET is an NMOS device. Specifically, each NMOS device includes a capacitor that is connected between the gate of the NMOS device and the pad terminal. A first resistor is connected between the gate and the p-well, while a second resistor is connected between the p-well and the grounded source. For a positive ESD pulse to VSS, the p-well is pulled up to approximately 0.7 V during the initial ESD event, such that the source junction is forward biased and that the trigger voltage of the NMOS device is lowered. At the same time the gate voltage is coupled within the range of approximately 1 to 2 V to promote the uniform turn on of the gate fingers of the NMOS devices during the initial ESD event.