Abstract: A nitride read only memory (NROM) erase system is disclosed. The NROM erase system comprises at least one memory sector, N sense amplifiers, and N buffers. The memory sector is segmented into N erase retry units according to the number of the sense amplifiers. One buffer corresponds with one erase retry unit and one sense amplifier. The N buffers are used to indicate whether their corresponding erase retry units are erased after an erase process of an erase operation. One of the buffers will be set if its corresponding erase retry unit is not erased. In this case, a subsequent erase process will begin to erase the un-erased erase retry unit. The erase retry units that are erased in a previous erase process will not be affected by the subsequent erase process. A method for using the disclosed NROM erase system is also described.

Abstract: A circuit and method for tuning a reference bit line loading to a sense amplifier that compares the voltage on a sense node with the voltage on a reference data line node to determine a sensing signal on the output of the sense amplifier. The sense node is selectively connected to a memory cell to generate the sensed voltage on the sense node to represent the data stored in the selected memory cell. There is included a reference cell unit and a reference bit line unit connected to the reference data line node. The reference cell unit contains at least one reference cell to provide a reference current to the reference bit line node, and the reference bit line unit contains at least one reference bit line optionally cut to determine the reference bit line loading.

Abstract: A circuit and method for tuning a reference bit line loading to a sense amplifier that compares the voltage on a sense node with the voltage on a reference data line node to determine a sensing signal on the output of the sense amplifier. The sense node is selectively connected to a memory cell to generate the sensed voltage on the sense node to represent the data stored in the selected memory cell. There is included a reference cell unit and a reference bit line unit connected to the reference data line node. The reference cell unit contains at least one reference cell to provide a reference current to the reference bit line node, and the reference bit line unit contains at least one reference bit line optionally cut to determine the reference bit line loading.

Abstract: A method for designing a circuit layout of non-neighboring metal bit lines to reduce coupling effect in sensing operation is disclosed. The method comprises providing a memory array having a plurality of bit lines arranged sequentially, wherein every two adjacent bit lines are paired in the sensing operation of a memory cell in the memory array. The first embodiment is presented by assigning a first pair of the bit lines permuted with each other to create a non-neighboring bit line layout. The second embodiment is presented by inserting one of a second pair of the bit lines into a first pair of bit lines to separate the first pair of bit lines in layout design. The method further comprises shrinking the layout space between two adjacent non-paired bit lines. In this way, the method contributes to the reduction of metal bit line coupling effect without any trade off of integrated circuit density by modifying the circuit layout of metal bit lines to a non-neighboring bit line arrangement in a memory array.

Abstract: A method for compensating a threshold voltage of a neighbor bit, are provided. The method includes the first step of arbitrating the word line voltages applied to bits demanded to be programmed, wherein the the word line voltages are arbitrated according to the threshold voltages of the neighbor bits adjacent to the bits. Next, the bits, to which a same word line voltage should be applied, in the memory cells are distributed to a group of bits with the same word line voltage. Then, the same word line voltage is applied to the bits of the group of bits with the same word line voltage.

Abstract: A method for compensating a threshold voltage of a neighbor bit, are provided. The method includes the first step of arbitrating the word line voltages applied to bits demanded to be programmed, wherein the the word line voltages are arbitrated according to the threshold voltages of the neighbor bits adjacent to the bits. Next, the bits, to which a same word line voltage should be applied, in the memory cells are distributed to a group of bits with the same word line voltage. Then, the same word line voltage is applied to the bits of the group of bits with the same word line voltage.

Abstract: A method and an integrated circuit for performing a soft program after erase provides efficient convergence of over-erased floating gate memory cells disposed in bit lines. The soft program is applied to successive subject bit lines. The BLISP method includes selection of a selected bit line and applying the soft program to a subject bit line corresponding to the selected bit line. For integrated circuits having no defective bit lines, the subject bit lines comprise the selected bit lines. The BLISP method is adapted for low current consumption compared to bulk soft programming methods. In some embodiments, the integrated circuit includes defective bit lines. For these integrated circuits, the selection of the selected bit line includes indicating a bit line type corresponding to the selected bit line. The defective bit lines are logically replaced by redundant bit lines so that the soft program is applied to conforming selected bit lines and redundant bit lines corresponding to defective bit lines.

Abstract: A method for designing a circuit layout of non-neighboring metal bit lines to reduce coupling effect in sensing operation is disclosed. The method comprises providing a memory array having a plurality of bit lines arranged sequentially, wherein every two adjacent bit lines are paired using in sensing operation of a memory cell in the memory array. The first embodiment is presented by assigning a first pair of the bit lines permuted with each other to create a non-neighboring bit line layout. The second embodiment is presented by inserting one of a second pair of the bit lines into a first pair of bit lines to separate the first pair of bit lines in layout design. The method further comprises shrinking the layout space between two adjacent non-paired bit lines. Thereby, the method contributes to the reduction of metal bit line coupling effect without any trade off of integrated circuit density by modifying the circuit layout of metal bit lines to a non-neighboring bit line arrangement in a memory array.

Abstract: An erase device and a method of erasing data from a flash memory. The erase device includes a shift control signal transmission terminal, an erase control group and a pulse control group. The shift control signal transmission terminal is used for transmitting a shift control signal. The erase control group includes a plurality of serially connected erase controllers. Each erase controller corresponds to a memory block. Each of the erase controllers contains a shift register, a receiving terminal and an output terminal. The receiving terminal of the first erase controller receives a shift control signal sent from the shift control signal transmission terminal. The receiver terminal of a subsequent erase controller connects electrically with the output terminal of the previous erase controller. In addition, the shift register contains a shift control signal received from the receiving terminal.

Abstract: A reference current is generated by inputting an adjusting current, which is about two or three micro amperes larger than the drain current of the NROM cell having a highest threshold voltage of the flash memory, a reference current with an initial value, effectively the same as the drain current of the NROM cell with a lowest threshold voltage. The method involves sensing the difference between the reference current decreasing from its initial value, and the adjusting current under a predetermined memory speed.

Abstract: A method for tracking metal bit line coupling effect in sensing a signal received from an array cell within a memory array is disclosed. The method includes that a reference unit with a reference cell is provided, wherein the reference unit induces coupling effect. Then, the memory array and the reference unit are charged to generate a cell signal having coupling effect and a reference signal having coupling effect. Next, a sensing signal is generated from the difference of the cell signal and the reference signal, whereby the coupling effect is compensated. In the read-out operation of the present invention, because of the closeness of two adjacent metal bit lines, the coupling effect is induced in both memory array and reference unit at the same time, so that the coupling effect is compensated. Therefore, precise read-out operation of data stored in a memory cell is made possible, and the reliability of the device is improved by the present invention.

Abstract: A non-volatile integrated circuit memory, such as a flash memory device based on floating gate transistor memory cells, with read while write capability is provided using a single address register. The integrated circuit includes at least two independent arrays of memory cells. During a program or an erase operation in one array on the non-volatile integrated circuit, a read operation can be executed in the other array on the same integrated circuit by bypassing the address register altogether, and allowing the register to remain in use by the program or erase operation. A bypass combinatorial logic path for the read process is coupled to the same address inputs as the address register, and operable in parallel with the registered address path.

Abstract: The present invention provides a new memory device for storage of boot code for microprocessors which boot to either the top or bottom of a memory map on power-up. The device includes a memory array, a first block, and decoders. The first block is defined as rows of the memory array designated for storage of data. The decoders decode a memory access requested for the data. The memory access request may be in either one of a top-down or bottom-up address protocol. In another embodiment, an integrated circuit memory includes: a memory array, a decoder, a control, and a logic gate. The decoders decode a memory access request to select a row of memory array. The control has an output for outputting either a bottom-up or a top-down address protocol signal. The logic gate outputs a logical "Exclusive Or" of the control signal and a corresponding bit of the memory access request, whereby a memory request in a bottom-up address protocol is converted to a memory address in a top-down address protocol.

Abstract: A circuit generates a power on reset signal in response to the changing of a supply potential across a supply node and a reference node from a power down level to a power on level. The circuit comprises a capacitor having a first terminal coupled to the supply node and a second terminal. An output driver, such as an inverter, is coupled between the supply node and the reference node. The output driver has an output coupled to the second terminal of the capacitor. An input driver comprises a circuit which drives the input of the output driver to a level which tracks changes in the supply potential. A clamp transistor, such as a n-channel MOS transistor having a lower threshold than normal transistors in the circuit, is coupled between the input of the output driver and the supply potential. The clamp transistor clamps the input of the output driver to a driver ready level which is below the trip point of the output driver when the supply potential is at a power down level.

Abstract: A circuit is provided for supplying a negative erasing voltage onto the wordlines of selected blocks in an array of floating gate memory cells. The circuit includes a voltage circuit, which has a plurality of local outputs, each of which connects to wordlines of an associated block of floating gate memory cells. A block selector circuit is coupled to the local outputs of the voltage circuit and selectively switches each of the local outputs to apply either an erasing voltage or a non-erasing voltage onto the wordlines of the associated block of floating gate memory cells. Negative wordline stress is thus reduced for wordlines of unselected blocks which receive a less negative, non-erasing voltage during block erase operations.

Abstract: A system for programming arrays of floating gate memory cells reduces programming current requirements, and reduces wordline and bitline stress during programming. A word-to-be-programmed into a floating gate memory array is divided into a plurality of smaller subwords. Only one subword is programmed at a time, thereby reducing programming current requirements. Additionally, subwords which are successfully programmed are not reprogrammed even if bits in other subwords do not program properly. This creates less wordline stress than previous systems which program an entire word at once, thereby requiring subwords which program successfully to be reprogrammed along with subwords which fail to program. Finally, within each subword only those bits which failed to program are reprogrammed, thereby reducing bitline stress during reprogramming for those bits which were successfully programmed.

Abstract: Substantial reduction in peak current encountered during an erase process for a flash memory device is achieved by selection of source voltage potential during the erase according to the expected band-to-band tunneling current encountered during the process. During the beginning of the process, a lower source voltage potential is selected, which is high enough to cause significant erasing while suppressing band-to-band tunneling current in a portion of the array, and during a second part of the erasing process, a higher source potential is utilized, which ensures successful erasing of the array, without exceeding the peak current requirements of the power supply used with the device. The first and second parts of the erase sequence will induce band-to-band tunneling current in addition to Fowler-Nordheim tunneling current. The band-to-band tunneling current is characterized by a turn on threshold source potential which is inversely related to the threshold of the cell receiving the voltage sequence.