International Business Machines Corporation

Vanguard International Semiconductor Corporation

Palomar Technologies, Inc.

Luigi Ternullo, Jr

John P Connor

Robert Dean Adams

Garrett Stephen Koch

Michael C Stephens, Jr

Randy William Mann

Werner A Rausch

Eric Adler

Jeffrey Scott Earl

Subhash Balakrishna Kulkarni

Donald Albert Evans

Roy Childs Flaker

James J Covino

Alan L Roberts

Jose Roriz Sousa

Christopher Ematrudo

Howard C Kirsch

Kenneth R Hesse

Esther Sluzky

Stuart D Rapoport

Marcel J Robillard

Stuart J Hall

Santosh K Kurinec

Michael F Vincent

A voltage regulation scheme for an on-chip voltage generator includes a voltage sensing circuit (VSC) and a configurable buffer circuit (CBC) to regulate the on-chip voltage generator. The CBC generates an output signal that is received by the on-chip voltage generator to activate and de-activate the voltage generator. The VSC generates a voltage level detection (VLD) signal having a voltage level that is a function of the level of the on-chip generated voltage. The CBC receives a control signal that is used to dynamically configure the chip into an operational mode, as well as the VLD signal. In response to the control signal, the switch threshold of the CBC is configured to a predetermined level corresponding to the selected operational mode. The predetermined trip point causes the CBC to appropriately activate and de-activate the on-chip voltage generator to regulate the on-chip generated voltage at the level required by the configured operational mode. One embodiment of the CBC uses a configurable pull-up circuit to alter its switch threshold or trip point. The configurable pull-up circuit is used to pull-up the voltage at an intermediate node that is buffered and propagated to the on-chip voltage generator to activate and de-activate the voltage generator. The configurable pull-up circuit more strongly pulls up this voltage in one operational mode compared to another operational mode to alter the switch threshold.

Dynamically adjustable on-chip supply voltage generation

True and complement data signals are provided to a multiplexer, which selects one of them based on a selection signal for capture by a single scannable latch in response to a clock signal. The scannable latch then provides the captured signal for testing by testing logic.

Method and apparatus for testing differential signals

A local bit switch selecting circuit and method for systems having a first number of banks of sense amplifiers with a second number of sense amplifiers in each sense amplifier bank. The bit switch selecting circuit and method use a single N channel field effect transistor in each sense amplifier bank. This provides bit switch selecting capability while significantly reducing the number of devices and chip area required.

Local bit switch decode circuit and method

A circuit for a DRAM is described which, when in test mode, notifies a tester when the self-refresh operation of a dynamic random access memory (DRAM) reaches various stages of completion. By signaling the tester when, i.e., &frac18;, &frac14;, &frac12;, etc. of the self-refresh cycle is reached, the amount of time needed for verification of the self-refresh oscillator frequency is reduced correspondingly by a factor of 8, 4, 2 etc. The signaling of a partial test time is achieved by adding self-refresh status logic circuits which decode the high order most significant bits of the refresh address counter. The activation of the third most significant bit signals completion of &frac18;th of the self-refresh cycle, the activation of the second most significant bit signals completion of &frac14;th of the self-refresh cycle, the activation of the most significant bit signals completion of &frac12; of the self-refresh cycle, and deactivation of the most significant bit signals completion of the self-refresh cycle.

Self-refresh test time reduction scheme

A charge pump limits the voltages at nodes internal to the charge pump to reduce the risk of junction breakdown in the charge pump. The charge pump includes a first pump circuit, a second pump circuit, a first clamp and a second clamp. The first clamp limits the voltage level of a well by providing a current path from the well to the output lead when the voltage level of the well reaches a first predetermined limit. The voltage level at a node from which charge is redistributed to the well is limited by the second clamp, which is configured to provide a conductive path from the node to the output lead when the voltage level of the node reaches a second predetermined limit. The pump circuits can each include a logic circuit that is configured, depending on the level of an external supply voltage, to reduce the rate at which the capacitor node is boosted when the external supply voltage is relatively high. The logic circuit can also vary the voltage difference between the capacitor node and the external supply voltage to decrease the relative voltage level at the capacitor node relative to the level of the external supply voltage. These features also help reduce the risk of junction breakdown in the charge pump.

Internal charge pump voltage limit control

A crow-bar current reduction circuit for use with a NMOS output circuit a gate voltage control circuit (GVC). The GVC receives a data signal and an output enable signal and generates control signals to drive the gates of the output transistors of the output circuit. When enabled, the GVC delays the rising edges of the gate control signals so as to help ensure that during a transition of the output signal generated by the output circuit, the NFET that was conductive before the transition is 'turned off' to become non-conductive before the NFET that was non-conductive before the transition is 'turned on' to become conductive. When adapted for a CMOS output circuit, the GVC delays the rising edge of the gate control signal provided to the NMOS pull-down transistor and delays the falling edge of gate control signal provided to the PMOS pull-up transistor.

Crow-bar current reduction circuit

A timing circuit can be selectively configured to generate output pulses in response to either the falling edges or the rising edges of an input signal. The timing circuit includes a multiplexer, an output pulse width controller (OPWC), a gating circuit (GC) and a latch circuit. The OPWC includes a delay circuit that can be configured to provide a predetermined delay .delta. that can be larger than the pulse width of the input signal pulses. The multiplexer is connected to receive a first input signal and an inverted version of a second input signal. The first input signal is used in a rising edge triggered mode, whereas the second input signal is used in a falling edge triggered mode. The multiplexer receives a mode signal to selectively output one of the input signals to the GC. The GC is also connected to receive the output signal from the OPWC. The OPWC is configured in conjunction with the selected signal from the multiplexer, to cause the GC and the latch circuit to generate output pulses having a predetermined pulse width equal to .delta., triggered by the rising edges of the selected signal. Because the second input signal is inverted, during the second mode the output pulses are in effect triggered by the falling edges of the second input signal.

Timing circuit that selectively triggers on a rising or falling input

A timing scheme for multiple data clock activation with programmable delay for use in accessing a multiple CAS latency memory device. A multi-stage data propagation path is used to propagate a bit being accessed from a memory array of the device to an output line. Timing signals are generated so that in a CAS latency three mode, the timing signal that activates the next to last stage of the propagation path is triggered by an output clock signal that activates the last stage of the propagation path so that pulse from the output clock signal does not overlap with pulses of the timing signal that activates the previous stage. This timing scheme ensures the data lines feeding the last stage are not being restored while the last stage is sensing these data lines. A programmable delay circuit is used to adjust the timing of the output clock signal.

Multiple data clock activation with programmable delay for use in

A regulator system for an on-chip-generated supply voltage includes a voltage detection circuit, a power-up mode detection circuit, a normal mode detection path, and a power-up detection path. The voltage detection circuit monitors the on-chip-generated supply voltage and generates a signal that indicates the level of this supply voltage. The power-up mode detection circuit detects when the chip is in the power-up mode and generates a path select signal. The path select signal causes the regulator system to select the power-up detection path during the power-up mode and to select the normal detection path when not in the power-up mode. The power-up detection path includes voltage regulation circuitry that does not rely on a reference voltage. In one embodiment, the power-up detection path includes a logic gate coupled to receive the signal from the voltage detector. The logic gate is skewed to have a trip point that corresponds to voltage level slightly greater than that of the external supply voltage. The logic gate controls the on-chip voltage generator to maintain the on-chip-generated voltage level at a magnitude greater than that of the external supply voltage. During power-up, the power-up detection circuit selects the power-up detection path, thereby avoiding the need to disable the on-chip voltage generator as in conventional systems that depend on a reference voltage.

On-chip-generated supply voltage regulator with power-up mode

The present invention provides a method and apparatus that accomplishes a high performance, random read/write SDRAM design by synchronizing the read and write operations at the data line sense amplifier. This enables the design to perform random read and write operations without varying cycle time issues or unbalanced margin issues. The data lines are used as bi-directional lines to accomplish high performance reads and writes with minimal additional wiring overhead required. During a read operation, read data is transferred from the memory cells of the device across a series of consecutive pairs of data lines to an input/output port of the memory device. The first pair of data lines is coupled to a data line sense amplifier. The additional pairs of data lines are coupled to additional amplifiers. During a read operation, data is transferred across the consecutive pairs of data lines according to the timing cycles of the respective amplifiers. In order to quickly drive the data signals during a write operation up the series of consecutive pairs of data lines, the timing signals for each of the pairs of data lines except the first pair of data lines are disabled so that the data lines are allowed to float, and then the data lines are overdriven with the write data so that the write data quickly transitions up the series of data lines to the selected data line sense amplifier, where it arrives at approximately the same time that read data normally arrives during the timing cycle for the data line sense amplifier.

High-speed synchronous write control scheme

A regulator system includes first and second voltage sensing circuits coupled to a voltage generator control circuit. The first and second voltage sensing circuits are configured to monitor the voltage generated by the on-chip voltage generator (i.e., the on-chip supply voltage) and detect when the on-chip supply voltage reaches thresholds that are predetermined to define a desired range of the on-chip supply voltage. The voltage generator control circuit receives voltage sense signals from the voltage sense circuits and, in response, asserts or de-asserts a control signal received by the on-chip voltage generator so as to activate or de-activate the on-chip voltage generator to maintain the on-chip supply voltage within the desired range. The voltage generator control circuit introduces hysteresis in the generation of the control signal provided to the on-chip voltage generator. As a result of this hysteresis, once the on-chip voltage generator is activated, the voltage generator control circuit only de-activates the on-chip voltage generator when the on-chip supply voltage reaches the higher threshold. Conversely, once the on-chip voltage generator is de-activated, the voltage generator control circuit only activates the on-chip voltage generator when the on-chip supply voltage reaches the lower threshold.

Regulator system for an on-chip supply voltage generator

The present invention is a system and method of testing logic circuits in memory of an integrated circuit in a fraction of the time. The present invention discloses a system and method to allow testing imbedded array logic blocks in parallel, rather than sequentially. The present invention allows for the testing of multiple logic blocks associated with different memory or column locations at the same time. This technique allows for reduction in test time by a factor of X, where X is the number of rows or columns or memory cells feeding logic.

Testing logic associated with numerous memory cells in the word or bit

A circuit for disabling a two-phase charge pump includes a pump select circuit and a disable control circuit. The pump select circuit is configured to select one control signal from a plurality of control signals in response to at least one select signal. The selected signal is in effect provided to the disable control circuit, which also receives a pump disable signal. A voltage sensing circuit asserts the pump disable signal when the pumped voltage reaches a predetermined maximum level. While the pump disable signal is de-asserted, the disable control circuit in effect provides the selected signal to the two-phase charge pump as a pump control signal. However, when the pump disable signal is asserted, the disable control signal latches the current logic level of the pump control signal so that the pump control signal does not transition while the pump disable signal is asserted. As a result, the two-phase charge pump is prevented from performing an extra pump cycle that would cause the pumped voltage to exceed the predetermined maximum level.

Method and circuit for disabling a two-phase charge pump

A method and apparatus for testing circuitry, such as a memory or a logic circuit, having a plurality of outputs, includes a built-in self-testing (BIST) test state machine for generating a plurality of address outputs, a plurality of multiplexers controlled by the address outputs of the test state machine, and a testing device for testing the plurality of outputs of the circuitry based on the address outputs of the test state machine. The plurality of outputs of the circuitry are input to the plurality of multiplexers and a number of outputs tested simultaneously is less than a total number of outputs of the circuitry.

Method and apparatus for achieving higher performance data compression

A memory Array Built-In Self-Test (ABIST) circuit is disclosed that will test a multi-port memory array. A programmable pattern generator for the ABIST circuit allows for different R/W data operations to be performed at the same or adjacent address locations within a multi-port memory array. The programmable pattern generator comprises a data generator, a read/write controller, and an address counter, each having the same number of outputs as ports of the multi-port memory array. The programmable pattern generator also comprises a frequency controller. The data generator is programmed with the appropriate data patterns for the memory array, and the read/write controller is programmed with the appropriate read/write patterns for the memory array. The address counter is to provide the same or different addresses on each port of the multi-port array, and the frequency controller is programmed with the appropriate frequency information to determine the number of read/write operations per cell in the memory array. The combination of programmable data, programmable read/write sequences, programmable address counter, and programmable frequency allows for determistic testing of a multi-port memory array, a plurality of single-port memory arrays, or a combination thereof by providing unique read/write sequences to the same or to adjacent memory locations.

Growing community of inventors

Colchester, VT, United States of America

Luigi Ternullo, Jr