Abstract: There is provided a tester interface circuit for use with a BIST state machine and a method for micro-architectural implementation of the same so as to enable cycling through a BIST test. The tester interface circuit includes a storage device, a logic decoder, a set/clear mechanism, and a polling logic device. The tester interface circuit is implemented with a minimum amount of chip area on a semiconductor IC.

Abstract: The present invention discloses a method and system to optimize electrical interconnection of electrical components in a periphery area of a memory device thereby minimizing the periphery area. The periphery area is divided into a plurality of sub-circuits formed by selectively electrically connecting the electrical components. Electrical interconnection of the electrical components to form the sub-circuits is accomplished using a first metal layer and a second metal layer. The first metal layer is formed to create a plurality of first metal layer lines that are oriented to extend in substantially one direction on the memory device. The second metal layer is formed to create a plurality of second metal layer lines that are oriented to extend substantially perpendicular to the first metal layer lines.

Abstract: A memory device is provided with reference cells that can be adapted to the core cells of the memory device. An erase verify reference cell. is adapted to the core cells by changing the threshold voltage of the erase verify reference cell until substantially all the core cells pass an erase verification test. A program verify reference cell is then setup by changing the threshold voltage of the program reference cell by a desired change in voltage between erased and programmed states. A read reference cell is also setup by changing the threshold voltage of the read reference cell so that it is intermediate of the erase verify reference cell and the program verify reference cell.

Abstract: The present invention discloses a voltage regulation method and system that provides a predetermined erase voltage to at least one wordline during a negative gate stress mode. A low-supply voltage negative charge pump is activated to generate a relatively high negative voltage. The relatively high negative voltage is regulated to the predetermined erase voltage by a regulator circuit. Regulation of the relatively high negative voltage is based on a variable reference voltage that is generated by a reference voltage circuit and directed to the regulator circuit. The predetermined reference voltage is capable of being varied within a first predetermined voltage range, thereby varying the predetermined erase voltage. The predetermined erase voltage is transferred to the wordlines by at least one decoder circuit during an erase operation.

Abstract: A method and system for controlling a boosted wordline voltage that is used during a read operation in a flash memory is disclosed by the present invention. In the preferred embodiment, a gate voltage is generated by a voltage booster in a wordline voltage booster circuit. An adjustable clamp circuit is electrically connected with the wordline voltage booster circuit for clamping the gate voltage that is generated by the voltage booster at a predetermined voltage level. The predetermined voltage level may be adjusted with a trimming circuit that is electrically connected to the adjustable clamp circuit, depending on process variations experienced during fabrication by the adjustable clamp circuit.

Abstract: The present invention discloses a wordline voltage regulation method and system that provides a predetermined voltage as a wordline voltage to a plurality of wordlines during read mode. A supply voltage (Vcc) is regulated and temperature compensated by a wordline driver circuit to provide the predetermined voltage that is lower in magnitude than the magnitude of the supply voltage (Vcc). The wordline driver circuit is activated by an activation circuit when the read operation is initiated. During the read operation, the wordline driver circuit maintains the predetermined voltage during variations in the supply voltage (Vcc) as well as variations in a process load supplied by the wordline driver circuit.

Abstract: The present invention discloses a method and system for activating a plurality of wordline decoder circuits to transfer a predetermined high voltage to a plurality of wordlines during a test mode in a memory device. A plurality of wordline voltage supply circuits supply voltage for the wordlines. During operation, when the memory device is placed in a test mode requiring application of the predetermined high voltage to the wordlines, the wordline decoder circuits are activated. In addition, a first predetermined voltage that is approximately zero volts is supplied by the wordline voltage supply circuits to the wordline decoder circuits for a first predetermined amount of time. Once the wordline decoder circuits decode the respective wordlines, the first predetermined voltage is transferred to the respective wordlines.

Abstract: When an array VT test mode is entered, a predetermined wordline voltage is generated by a wordline voltage supply and supplied to at least one decoder circuit and a voltage control logic circuit. The voltage control logic circuit generates a predetermined control voltage that is directed to the decoder circuits. The predetermined control voltage activates the decoder circuits. A particular decoder circuit is electrically selected to decode at least one respective wordline and transfer the predetermined wordline voltage to the respective wordline. The activated decoder circuits that are not electrically selected are not forward-biased.

Abstract: The present invention discloses methods and systems of wordline voltage protection to supply voltage to a plurality of wordlines in a memory device only during a read mode and a write mode. In the preferred embodiment, at least one wordline voltage protection circuit controls at least one decoder circuit that is activated to transfer voltage from at least one wordline voltage supply circuit to at least one wordline. The wordline voltage protection circuit activates the decoder circuit to transfer voltage to the wordline when the voltage is within a predetermined range and the memory device is performing one of a plurality of functions that include the write mode. The wordline voltage protection circuit also activates the decoder circuit to transfer voltage to the wordline when the memory device is performing one of a plurality of functions that include the read mode.

Abstract: A reference trimming verify circuit and method is provided for performing a program verify operation on a reference cell transistor in an array of Flash EEPROM memory cells. A reference current branch is used to generate a reference current corresponding to a predetermined overdrive voltage of the reference cell to be programmed. A drain current branch is coupled to the reference cell transistor to be programmed and generates a drain current at a fixed gate voltage applied to its control gate and at a predetermined drain voltage applied to its drain when the drain current is at the desired level. A comparator is used to compare a sensed voltage corresponding to the drain current and a reference voltage corresponding to the reference current. The comparator generates an output signal which is at a low logic level when the sensed voltage is less than the reference voltage and which is at a high logic level when the sensed voltage is greater than the reference voltage.

Abstract: A flash Electrically-Erasable Programmable Read-Only Memory (EEPROM) includes a plurality of field effect transistor memory cells, a power supply, and a controller which cooperates with the power supply to apply an erase pulse to the cells, and then erase verify a first byte of cells in each sector. If the first bytes in any sector has not passed erase verify, another erase pulse is applied to the cells of those sectors, and the first byte in each sector which did not pass erase verify the first time is erase verified again. This procedure is continued until the first byte in each sector has passed erase verify. Then, the sectors are processed in sequence to erase and erase verify every cell. First, an erase pulse is applied to all of the cells in the sector. Then, the first byte is erase verified. If the first byte passes erase verify (which it will because it did previously), the next byte is erase verified.

Abstract: A wordline tracking structure for use in an array of Flash EEPROM memory cells is provided. The tracking structure serves to match reference and sector core wordline voltages across the entire chip regardless of sector location. The tracking structure includes a second VPXG conductor line operatively connected between sector wordlines of a "far" sector and a reference cell mini-array. The second VPXG conductor line has a substantially smaller time constant than in a first VPXG conductor line operatively connected between an output of a boosting circuit and the sector wordlines of the "far" sector. As a consequence, the reference wordline voltage associated with the reference cell mini-array will track closely the sector wordline voltage during the read operation regardless of the location of the selected sector.

Abstract: A flash Electrically-Erasable Programmable Read-Only Memory (EEPROM) includes a plurality of floating gate transistor memory cells, a plurality of wordlines connected to the cells and a power supply for generating erase pulses. A controller controls the power supply to apply an erase pulse to all wordlines which are not deselected. Then, an erase verify procedure is applied to the cells in sequence. If all cells connected to a wordline pass the erase verify test, the wordline is deselected such that subsequent erase pulses will not be applied to the wordline and possibly cause the cells to become overerased. In one embodiment of the invention, erase verify is performed on all of the cells after an erase pulse is applied. The erase operation is completed when all cells pass erase verify. In another embodiment, erase verify is applied to each cell in sequence, with erase pulses being applied until each current cell passes erase verify. The wordlines can be deselected individually or in groups.

Abstract: The present invention discloses a method for saving overhead programming time in a flash memory. In the preferred embodiment of the invention, a wordline voltage generation circuit and a bitline voltage generation circuit are electrically connected with a comparator circuit. During the programming operation, the comparator circuit compares a wordline programming voltage and a bitline enabling voltage generated by the voltage generation circuits to determine when the programming voltages reach a predetermined voltage level. Once the predetermined voltage level is reached, the comparator circuit sends an output signal to a state machine that initiates programming for at least one cell. The present invention provides advantages over prior methods of programming by reducing the time period that the state machine waits to initiate programming.

Abstract: A flash Electrically-Erasable Programmable Read-Only Memory (EEPROM) includes a plurality of floating gate transistor memory cells, a plurality of wordlines connected to the cells and a power source for generating a low power supply voltage on the order of 3 V or less. A wordline driver includes a booster for boosting the supply voltage to produce a wordline read voltage which is higher than the supply voltage, and applying the wordline voltage to a wordline. An upper clamp limits a maximum value of the wordline voltage to prevent read disturb. The upper clamp can be configured to reduce an amount by which the maximum value varies with the supply voltage, or to limit the maximum value to substantially a predetermined value.

Abstract: The present invention discloses a CFI bit line decoder for a memory device that is capable of storing common flash interface data. In the preferred embodiment, the CFI bit line decoder has at least one bit line decoder circuit including at least one pass gate and a plurality of bit line pass gates, wherein each pass gate is electrically connected with at least one pass gate. In addition, the CFI bit line decoder includes at least one CFI storage circuit that has at least one storage cell electrically connected with the bit line decoder circuit. Each storage cell is in turn electrically connected with the bit line pass gate of the bit line decoder circuit. During CFI mode, a vertical address signal is used to enable a respective pass gate and a CFI address signal is used to enable a respective storage cell. A read circuit is then used to sense the logic state of the storage cell so that a peripheral device can use the data.

Abstract: The present invention discloses a memory wordline decoder that includes a plurality of pre-decoded address lines that are electrically connected with a global x-decoder. A sub x-decoder is electrically connected with the global x-decoder for receiving electrical control signals from the global x-decoder. A memory sector is electrically connected with the sub x-decoder. The global x-decoder selectively controls the sub x-decoder to select a plurality of wordlines in the memory sector. A vertical x-decoder is electrically connected with the global x-decoder and the sub x-decoder. The vertical x-decoder is used to select a predetermined wordline by the global x-decoder during operation.

Abstract: A flash Electrically-Erasable Programmable Read-Only Memory (EEPROM) includes a plurality of field effect transistor memory cells each having a source, drain, floating gate and control gate, and a power source for supplying a plurality of voltages to the cells. A controller controls the power source to apply at least one erase pulse to the cells. Then, at least one overerase correction or "soft programming" pulse is applied to the cells during which the source, drain and control gate voltages of the cells are such that the threshold voltages of overerased cells will be increased, but least erased cells will not be disturbed. The overerase correction pulses thereby tighten the threshold voltage distribution. A source to substrate bias voltage is applied for the duration of the overerase correction pulses which reduces the background leakage of the cells to a level at which the overerase correction operation can be effectively performed, even in applications with low supply voltages.

Abstract: A flash Electrically-Erasable Programmable Read-Only Memory (EEPROM) includes a semiconductor substrate, and a plurality of field effect transistor memory cells each having a source, drain, floating gate and control gate formed on the substrate. A controller controls a power source to apply an operational pulse to the drain of a cell, and apply a source to substrate bias voltage to the cell while the operational pulse is being applied thereto, the bias voltage having a value selected to reduce or substantially eliminate leakage current in the cell. The operational pulse can be an overerase correction pulse. In this case, a voltage which is substantially equal to the bias voltage is applied to the control gate for the duration of the overerase correction pulse. The operational pulse can also be a programming pulse. In this case, a voltage which is higher than the bias voltage is applied to the control gate of the selected wordline for the duration of the programming pulse.

Abstract: An improved programming structure for performing a program operation in an array of multiple bits-per-cell flash EEPROM memory cells is provided. A memory core array (12) includes a plurality of memory cells and a reference cell array (22) having a plurality of reference core cells which are selected together with a selected memory core cell. A precharge circuit (36a) is used to precharge all of the array bit lines and the reference bit lines to a predetermined potential prior to a program operation. A reference generator circuit (134) is used for selectively generating one of a plurality of target memory core cell bit line program-verify voltages, each one corresponding to one of a plurality of programmable memory states. A switching circuit (P1,N1) is used to selectively connect a program current source to the selected certain ones of the columns of array bit lines containing the selected memory core cells which are to be programmed.