Abstract: A memory cell array is physically divided into an even number of sectors, with each pair of sectors sharing read circuitry. The outputs of the shared read circuitry are commonly connected to form data lines spanning the height of the array, which are input to global sense amplifiers. A two-stage sensing scheme is employed, with first stage and global sense amplifiers. The driving capability of the first stage sense amplifier can be used to decrease the time to charge or discharge the data lines, which reduces the total signal development time and consequently improves read performance. Granularity of the array can be adjusted by dividing groups and sub-groups of memory cells within a sector accordingly. In a read operation, the bit line in the opposite sector at the same column location is used as reference bit line, which greatly improves matching of bit line loading for the sensing.

Abstract: A sense amplifier circuit includes a latch circuit to enhance the speed of a sensing operation and to obviate the need for a latch circuit to capture the output value of the sense amplifier circuit. In one embodiment, first and second differential amplifiers provide a differential signal to the latch circuit. The high gain in the latch circuit resolves the differential signal to a logic signal, which is then provided to an output amplifier. In one embodiment, the differential signal is provided to the latch circuit after the differential signal across the input terminals of the first and second differential amplifiers exceeds a predetermined value.

Abstract: A microcontroller memory system that provides on-chip, non-volatile memory for internal data and program code storage in such a manner that all on-chip, non-volatile memory is efficiently utilized. In one embodiment, a microcontroller memory scheme allows internal program code and data stored in the non-volatile memory to be reprogrammed in place by software executing on the microcontroller or by external devices through the microcontroller's serial port. In another embodiment, data and program code stored in the internal program area can be accessed using any instruction employed to access via an internal data bus the contents of an on-chip, volatile memory. The non-volatile memory used to store the program code and internal data can be implemented with Flash memory or EEPROM.

Abstract: A single-poly, floating gate memory cell includes a PMOS write and an NMOS read path. The memory cell's write path includes a PMOS half-transistor coupled in series with a PMOS write select transistor. The PMOS half-transistor serves as a storage element and includes a P+ drain region, a polysilicon floating gate, and a buried control gate. The read path includes an NMOS read transistor coupled in series with an NMOS read select transistor, where the floating gate of the PMOS half-transistor programming element serves as the gate of the NMOS read transistor. The memory cell is programmed along the PMOS write path by injecting electrons from a P-channel region of the PMOS half-transistor into the floating gate, and is read along the NMOS read path by conducting a channel current through an N-channel region of the NMOS read transistor.

Abstract: A semiconductor memory includes cell array having a plurality of bit lines connected to respective input terminals of a column decoder. Input/output (I/O) lines are connected between respective output terminals of the column decoder and a plurality of sense circuits, where each sense circuit includes its own reference circuit, a sense amplifier, and equalizing circuit. The reference circuit includes a reference array essentially identical to the cell array and provides a reference voltage to respective first input terminals of its associated equalizing circuit and sense amplifier. Second input terminals of the equalizing circuit and sense amplifier of each sense circuit are connected to a corresponding I/O line. During read operations, the equalizing circuits are initially maintained in a conductive state so as to equalize the I/O line voltage and the reference voltages. Thereafter, the equalizing circuits transition to a non-conductive state so as to isolate the I/O line from the reference voltage.

Abstract: A page buffer facilitates programming of a memory cell within an associated memory array by selectively connecting a bit line associated with the memory cell to a negative voltage supply in response to the logic state of a data signal. The page buffer includes an SRAM latch having first and second nodes, a cross-coupled latch having first and second nodes, and a pass transistor. The first node of the SRAM latch is coupled to receive the data signal and to a first control terminal of the cross-coupled latch. The second node of the SRAM latch is coupled to a second control terminal of the cross-coupled latch. The second node of the cross-coupled latch is coupled to a gate of the pass transistor which, in turn, is connected between the bit line and the negative voltage supply. When the data signal is in a first logic state, the cross-coupled latch turns on the pass transistor and, in connecting the bit line to the negative voltage supply, facilitates programming of the cell.

Abstract: A program voltage of a first level is applied to the control gate of a PMOS floating gate memory cell to realize an injection of hot electrons induced by band-to-band tunneling (BTBT) into the floating gate of the cell. As the threshold voltage of the cell increases due to the accumulation of charge on the floating gate, the injection of BTBT induced hot electrons subsides. The program voltage is reduced to a second level which induces the injection of channel hot electrons (CHE) into the floating gate, thereby boosting the rate of charge accumulation on the floating gate.

Abstract: A circuit for generating a boosted voltage includes a logic portion and a switching portion. The logic portion is coupled to receive a clock signal and, in response thereto, provides control signals to an associated switching circuit. During a first portion of the clock signal cycle, the switching circuit pulls an output terminal of the circuit to the supply voltage. During a second portion of the clock signal cycle, the switching circuit utilizes a bootstrap capacitor to boost the output terminal of the circuit to approximately twice the supply voltage, while isolating the output terminal from the supply voltage.

Abstract: A non-volatile latch is disclosed which includes four PMOS floating gate memory cells arranged in a 2.times.2 matrix. Binary data values are written to the latch by the threshold voltage of the cells, where a first binary value is written by programming all the cells, and the second binary value is written by leaving all the cells in an erased state. Thus, since a program operation is required when writing only one of the binary value, high program voltages and floating gate charge times are eliminated when writing the other binary value. After a read operation in which the binary value stored in the cells is provided as output, this binary value is automatically latched in a latch circuit. In this manner, subsequent reads to the latch do not require accessing the cells.

Abstract: A nonvolatile PMOS memory array includes a plurality of pages, where each column of a page includes two series-connected PMOS OR strings in parallel with a bit line. Each PMOS OR string includes a PMOS select transistor coupled between the bit line and two series connected PMOS floating gate memory cells. The PMOS floating gate memory cells are programmed via channel hot electron (CHE) injection and erased via electron tunneling. A soft-program mechanism is used to compensate for over-erasing of the memory cells. In some embodiments, the bit lines are segmented along page boundaries to increase speed.

Abstract: A semiconductor memory includes a plurality of memory cells and a corresponding plurality of page buffers. When writing to a selected row of cells, input data is first latched into the page buffers. The cells in the selected row are then programmed according to the data latched within the page buffers. After programming, data stored in the cells is forwarded to the corresponding page buffers. If, for each cell, the data stored in the cell matches the data latched in its corresponding page buffer, the page buffer is reset. The selected row of cells are subsequently re-programmed, whereby only cells corresponding to those page buffers which have not been reset are re-programmed. In this manner, cells properly programmed during the first program operation are not re-programmed during program verify operations.

Abstract: A P-channel single-poly EPROM cell has P+ source and P+ drain regions, and a channel extending therebetween, formed in an N-type well. A thin layer of tunnel oxide is provided over the channel and, in some embodiments, over significant portions of P+ source and P+ drain regions. A poly-silicon floating gate overlies the tunnel oxide. A P diffusion region is formed in a portion of the N-well underlying the floating gate and is thereby capacitively coupled to the floating gate. In this manner, the P diffusion region serves as a control gate for the memory cell. Programming is accomplished by coupling a sufficient voltage to the floating gate via the control gate while biasing the source and drain regions to cause the hot injection of electrons from the N-well/drain junction to the floating gate, while erasing is realized by biasing the floating gate, N-well, source and drain regions appropriately so as cause the tunneling of electrons from the floating gate to the N-well, the source, and the drain.

Abstract: A memory array includes a predetermined number of rows of PMOS Flash memory cells formed in each of a plurality of n- well regions of a semiconductor substrate, where each of the n- well regions defines a page of the memory array. In some embodiments, a plurality of bit lines define columns of the memory array, where the p+ drain of each of the memory cells in a common column are coupled to an associated one of the bit lines. In other embodiments, a plurality of sub-bit lines define columns of the memory array, where the p+ drain of each of the memory cells in a common column are coupled to an associated one of the sub-bit lines, and groups of a predetermined number of the sub-bit lines are selectively coupled to associated ones of a plurality of bit lines via pass transistors.

Abstract: A sensing circuit charges the bit lines of an associated memory array using one or more large-area pass transistors during reading operations of a selected memory cell of the memory array. In this manner, the read speed of the memory array is independent of the channel current of the memory cell. A sink transistor sinks a constant current from the selected bit line during reading to improve the noise margin of the sensing circuit so that memory arrays associated with the sensing circuit do not require the reference bit lines.

Abstract: A row decoder circuit selectively provides suitable programming, reading, and erasing voltages to an associated memory array employing PMOS floating gate transistors as memory cells. In some embodiments, during programming, the row decoder circuit pulls a selected word line of the associated memory array high to a programming voltage on a first voltage line and maintains an un-selected word line at a predetermined potential. During reading, the row decoder circuit discharges the word line, if selected, to ground potential, and maintains the word line, if un-selected, at a predetermined potential. During erasing, the row decoder circuit charges the word line to a high negative voltage. The row decoder circuit includes isolation means to electrically isolate the word line of the associated memory array from undesirable potentials during programming, reading, and erasing operations.

Abstract: A non-volatile memory latch device includes two PMOS memory cells and a cross-coupled static latch having two PMOS transistors and two NMOS transistors. The floating gates of each PMOS memory cell/transistor pair are coupled together. The control gates of all four PMOS devices are commonly connected to an input. The latch is programmed by applying -3 to -8 volts to the drain of one of the PMOS memory cells, floating the drain of the other PMOS memory cell, and applying 7 to 11 volts to the control gates of all four PMOS devices. The latch is erased by applying 3 to 8 volts to both drains of the PMOS memory cells and -7 to -11 volts to the control gates of all four PMOS devices. Lower programming and erasing voltages are possible with the PMOS latch, as compared with conventional NMOS latches.

Abstract: A row decoder circuit selectively provides suitable programming, reading, and erasing voltages to an associated memory array employing PMOS floating gate transistors as memory cells. In some embodiments, during programming, the row decoder circuit pulls a selected word line of the associated memory array high to a programming voltage on a first voltage line and maintains an un-selected word line at a predetermined potential. During reading, the row decoder circuit discharges the word line, if selected, to ground potential, and maintains the word line, if un-selected, at a predetermined potential. During erasing, the row decoder circuit charges the word line to a high negative voltage. The row decoder circuit includes isolation means to electrically isolate the word line of the associated memory array from undesirable potentials during programming, reading, and erasing operations.

Abstract: A switching circuit is disclosed herein which prevents an unwanted forward biasing of P/N junctions therein while allowing voltages exceeding the supply voltage to be provided in a precise manner to such floating gate memory cells. In accordance with the present invention, a switching circuit includes a first stage which effectively isolates programming voltages from supply voltages during programming and erasing operations, thereby allowing program and erase voltages exceeding supply voltage to be provided to an associated memory array. The switching circuit includes a second stage which prevents the unwanted forward-biasing of P/N junctions within the switch and its associated memory array by controlling the discharge rate of internal node when transitioning from either a programming or erasing operation to a read operation.

Abstract: A P-channel single-poly non-volatile memory cell having P+ source and P+ drain regions and a channel extending therebetween is formed in an N-type well. An overlying poly-silicon floating gate is separated from the N-well by a thin oxide layer. A P-type diffusion region is formed in a portion of the N-well underlying the floating gate and is thereby capacitively coupled to the floating gate. Within this P-type diffusion area lies an N-type diffusion area which serves as the control gate for the cell. The P-type diffusion region electrically isolates the control gate from the N-well such that voltages may be applied to the control gate in excess of those applied to the N-well without creating a current path from the control gate to the N-well. Programming is accomplished by coupling a sufficient voltage to the floating gate via the control gate while biasing the source and drain regions so as to cause the tunneling of electrons from the P+ drain region of the cell to the floating gate.

Abstract: A P-channel single-poly EPROM cell has P+ source and P+ drain regions, and a channel extending therebetween, formed in an N-type well. A thin layer of tunnel oxide is provided over the channel and, in some embodiments, over significant portions of P+ source and P+ drain regions. A poly-silicon floating gate overlies the tunnel oxide. A P diffusion region is formed in a portion of the N-well underlying the floating gate and is thereby capacitively coupled to the floating gate. In this manner, the P diffusion region serves as a control gate for the memory cell. Programming is accomplished by coupling a sufficient voltage to the floating gate via the control gate while biasing the source and drain regions to cause the hot injection of electrons from the N-well/drain junction to the floating gate, while erasing is realized by biasing the floating gate, N-well, source and drain regions appropriately so as cause the tunneling of electrons from the floating gate to the N-well, the source, and the drain.