Abstract: A differential buffer circuit includes a current source, a current sink, and a switching circuit connected to the current source at a first node and connected to the current sink at a second node. The switching circuit is operative to selectively control a direction of current flowing through differential outputs of the buffer circuit in response to at least a first control signal. The buffer circuit further includes a common mode detection circuit and a common mode control circuit. The common mode detection circuit is operative to detect an output common mode voltage of the buffer circuit and to generate a second control signal representative of the output common mode voltage. The common mode control circuit includes a first terminal connected to the current source and a second terminal connected to the current sink. The common mode control circuit is operative to selectively control the output common mode voltage of the buffer circuit as a function of the second control signal.

Abstract: A compensation circuit comprises a reference circuit including a reference NMOS device and a reference PMOS device. The reference circuit is operative to generate a first reference signal and a second reference signal, the first reference signal being a function of at least one of a process characteristic, a voltage characteristic and a temperature characteristic of the reference NMOS device, and the second reference signal being a function of at least one of a process characteristic, a voltage characteristic and a temperature characteristic of the reference PMOS device. The compensation circuit further comprises a control circuit connected to the reference circuit.

Abstract: A circuit for defining a voltage potential of a floating well in which is formed at least one metal-oxide-semiconductor device includes a sense circuit operative to detect a voltage at a node to which the floating well is connected and to generate a control signal indicative of whether the voltage at the node is substantially within a voltage range. A lower value of the voltage range is substantially equal to a threshold voltage below a first supply voltage of the circuit. An upper value of the voltage range is substantially equal to a threshold voltage above the first supply voltage. The circuit for defining the voltage potential of the floating well further includes a voltage generator circuit operative to receive the control signal and to generate a bias signal for setting a voltage potential of the well in response to the control signal, the bias signal being controlled throughout the voltage range.

Abstract: A PUR circuit for generating a reset signal includes a first node for receiving a reference voltage and a second node for receiving a supply voltage that is referenced with respect to the reference voltage. The circuit further includes a voltage level detector coupled between the first node and a third node, the voltage level detector being configured to generate a first control signal at the third node. The voltage level detector includes a first transistor having a first threshold voltage associated therewith. A resistance element is coupled between the second node and the third node, the resistance element having a first resistance value associated therewith. The circuit also includes an inverter having an input coupled to the third node and having an output for generating a second control signal in response to the first control signal. The inverter includes a second transistor having a second threshold voltage associated therewith which is lower than the first threshold voltage.

Abstract: A buffer circuit operative at multiple power supply voltage levels includes first and second buffers, the first buffer being configured for operation with a first voltage source and the second buffer being operative with a second voltage source. The buffer circuit further includes a controllable isolation circuit. An output of the first buffer connects to an external pad of the buffer circuit, and an output of the second buffer connects to the pad via the isolation circuit. The buffer circuit is selectively operative in at least a first mode or a second mode in response to at least a first control signal. The isolation circuit is operative in the first mode to substantially isolate the second buffer from the external pad and is operative in the second mode to connect the output of the second buffer to the external pad.

Abstract: Methods, apparatus, and other mechanisms are disclosed for merging lookup results, such as from one or more associative memory banks and/or memory devices. An access list is identified. A first set of entries corresponding to a first feature of the access control list entries and a second set of entries corresponding to a second feature of the access control list entries are identified. First and second associative memory banks are programmed respectively based on the first and second sets of entries. Lookup operations are then typically performed substantially simultaneously on the first and second sets of associative memory entries programmed in the associative memory banks to generate multiple lookup results, with these results typically being identified directly, or via a lookup operation in an adjunct memory or other storage mechanism. These lookup results are then combined to generate a merged lookup result.

Abstract: A buffer circuit having enhanced overvoltage protection includes core buffer circuitry couplable to a first voltage source having a first voltage level. The core buffer circuitry is configured to receive a first signal and to generate a second signal which is a function of the first signal. The buffer circuit further includes a protection circuit coupled between the core buffer circuitry and a signal pad. The protection circuit is operative: (i) to clamp the first signal to about the first voltage level when a third signal received at the signal pad exceeds the first voltage level by a first amount; and (ii) to generate the first signal being substantially equal to the third signal when the third signal is less than or substantially equal to the first voltage level.

Abstract: Methods, apparatus, and other mechanisms are disclosed for merging lookup results, such as from one or more associative memory banks and/or memory devices. In one exemplary implementation, multiple associative memories or associative memory banks are configured to substantially simultaneously generate a plurality of lookup results based on a lookup value. Multiple memories are each configured to generate a corresponding result based on the lookup result generated by its corresponding associative memory or associative memory bank. A combiner is configured to receive and merge these corresponding results generated substantially simultaneously in order to identify the merged lookup result.

Abstract: A voltage level translator circuit is selectively operable in one of at least two modes in response to a control signal. In a first mode, the voltage level translator circuit is operative to translate an input signal referenced to a first source providing a first voltage to an output signal referenced to a second source providing a second voltage. In a second mode, the voltage level translator circuit is operative to provide a signal path from an input of the voltage translator circuit to an output thereof without translating the input signal. The control signal is indicative of a difference between the first voltage and the second voltage.

Abstract: A network element is disclosed that provides redundancy within the network element that, in turn, provides fault tolerance for the failure of one or more processing units therein. In one embodiment, a network element according to the present invention includes N interface units, M processing units and a number of links. The value of N is an integer greater than 1. Each interface unit is coupled to L+1 processing units. The value of L is an integer greater than 0 and less than N, and the value of M equals N plus L. Each of the links is configured to couple one of the interface units and one of the processing units. Each of the interface units is configured to select one of the links that couples the interface unit and ones of the processing units, and the links include a primary link and a standby link.

Abstract: An ESD clamp circuit for use between separate power rails. An ESD clamp is based on a wide nMOSFET. A symmetrical circuit is designed vis-à-vis the two power rails, with respect to ground, allowing discharge of an ESD surge in both polarities of stress. An nMOSFET device drives the gate of a large nMOSFET (e.g., having a device width between 1000 and 10,000 microns). The large power rail-to-power rail nMOSFET has its gate controlled by the output inverter stage of either ESD detection circuit connected to a respective power supply rail. The gate is switched to a common ground during normal operation of the integrated circuit.

Abstract: A comparator circuit includes a reference generator connecting to a first source providing a first voltage. The reference generator is operative to generate a reference signal and includes a control circuit selectively operable in at least a first mode or a second mode in response to a first control signal, wherein in the first mode the reference signal is not generated, and in the second mode the reference generator is operative to generate the reference signal. The comparator circuit further includes a comparator connecting to a second source providing a second voltage, the second voltage being less than the first voltage. The comparator is operative to receive the reference signal and an input signal, and to generate an output signal which is a function of a comparison between the input signal and the reference signal.

Abstract: A voltage level translator circuit is selectively operable in one of at least two modes in response to a control signal. In a first mode, the voltage level translator circuit is operative to translate an input signal referenced to a first source providing a first voltage to an output signal referenced to a second source providing a second voltage. In a second mode, the voltage level translator circuit is operative to provide a signal path from an input of the voltage translator circuit to an output thereof without translating the input signal. The control signal is indicative of a difference between the first voltage and the second voltage.

Abstract: When a P-channel pass gate transistor is added in parallel to an N-channel pass gate, the resulting circuit improves overvoltage tolerance of an input buffer. A simple bias circuit including two small transistors controls a gate of this P-channel pass gate transistor in such a way that it is turned OFF when an overvoltage is applied, but turned ON when a normal voltage is applied. Another embodiment has two N-channel devices (M12, M13) coupled in series with each other and one of the N-channel devices (M13) being configured in a “turned off” position, by coupling the source and gate terminals to a ground voltage (VSS) and providing the supply voltage (VDD) at the gate terminal of another N-channel device (M12), whereby the device M12 protects the device M13 from overvoltage.

Abstract: A comparator circuit includes a reference generator connecting to a first source providing a first voltage. The reference generator is operative to generate a reference signal and includes a control circuit selectively operable in at least a first mode or a second mode in response to a first control signal, wherein in the first mode the reference signal is not generated, and in the second mode the reference generator is operative to generate the reference signal. The comparator circuit further includes a comparator connecting to a second source providing a second voltage, the second voltage being less than the first voltage. The comparator is operative to receive the reference signal and an input signal, and to generate an output signal which is a function of a comparison between the input signal and the reference signal.

Abstract: A comparator circuit having reduced pulse width distortion includes a differential amplifier operative to receive at least first and second signals and to amplify a difference between the first and second signals. The differential amplifier generates a difference signal at an output thereof which is a function of the difference between the first and second signals. An output stage is included in the comparator circuit for receiving the difference signal and for generating an output signal of the comparator circuit, the output signal being representative of the difference signal, the output stage having a switching point associated therewith. The comparator circuit further includes a voltage source coupled to the output of the differential amplifier. The voltage source is operative to generate a reference signal for establishing a common-mode voltage of the difference signal generated by the differential amplifier.

Abstract: A bias circuit includes a reference generator for generating a bias signal at an output of the reference generator. The reference generator is selectively operable a first mode or a second mode in response to a first control signal applied to the reference generator, wherein in the first mode of operation, the reference generator is disabled, and in the second mode of operation, the reference generator is operative to generate the bias signal. The bias circuit further includes a shunt circuit connected to the reference generator. The shunt circuit is configured to provide a source of current to assist in charging the output of the reference generator to a quiescent operating level during the second mode of operation. The shunt circuit, in response to a second control signal applied thereto, is operable for a selected period time after the reference generator transitions from the first mode of operation to the second mode of operation.

Abstract: A voltage level translator circuit for translating an input signal referenced to a first voltage level to an output signal referenced to a second voltage level includes an input stage for receiving the input signal. The input stage includes at least one transistor device having a first threshold voltage associated therewith. The voltage level translator circuit further includes a latch circuit operative to store a signal representative of a logical state of the input signal. The latch circuit includes at least one transistor device having a second threshold voltage associated therewith, the second threshold voltage being greater than the first threshold voltage. A voltage clamp is operatively connected between the input stage and the latch circuit, the voltage clamp being configured to limit a voltage across the input stage based, at least in part, on a control signal presented thereto.

Abstract: A semiconductor resistor circuit having a controllable resistance associated therewith includes a plurality of resistor segments connected in a series and/or parallel configuration. The resistor circuit further includes a plurality of switches controlling connection of respective ones of the resistor segments to the resistor circuit, to thereby selectively control a resistance of the resistor circuit in response to respective control signals presented to the switches. The resistor circuit is selectively controllable in discrete resistance intervals, the resistance intervals being unequal to one another. The resistor segments have resistance values that are selected such that a percentage resistance variation across each of the respective resistance intervals as a function of process, voltage and/or temperature conditions to which the resistor circuit is subjected is substantially the same.

Abstract: When a P-channel pass gate transistor is added in parallel to an N-channel pass gate, the resulting circuit improves overvoltage tolerance of an input buffer. A simple bias circuit including two small transistors controls a gate of this P-channel pass gate transistor in such a way that it is turned OFF when an overvoltage is applied, but turned ON when a normal voltage is applied. Another embodiment has two N-channel devices (M12, M13) coupled in series with each other and one of the N-channel devices (M13) being configured in a “turned off” position, by coupling the source and gate terminals to a ground voltage (VSS) and providing the supply voltage (VDD) at the gate terminal of another N-channel device (M12), whereby the device M12 protects the device M13 from overvoltage.