Mostek Corporation

Thomson Components-Mostek Corporation

Sgs-Thomson Microelectronics Limited

Robert J Proebsting

Paul R Schroeder

Donald R Dias

James E O'Toole

Harold L Davis

Sargent S Eaton, Jr

Daniel C Guterman

Horst Leuschner

Robert S Green

Andrew C Graham

Dennis L Segers

Robert John Paluck

Dennis R Wilson

A planar array of memory cells is controlled by row lines (word lines) for each row of cells and column lines each serving adjacent columns of cells as well as bit lines interlaced with the column lines so that all memory cells are connected between a column line and a bit line. The least significant bit of the column address provided by the column decoder selects between two sets of bit lines that are interlaced in altercation determining on which side of the column line the selected column will be found. In consequence, the selection of the column line and a set of bit lines selects only one column of cells. Enough columns of the array are selected at one time to address an entire logical field of data bits and also a set of parity bits related to the logical field of data bits. Each row of cells contain L (=16) logical fields, the individual data and parity cells of which are separated from each other by one cell of each of the other logical fields, so that a localized malfunction of the integrated circuit will not produce an error in more than one bit of any one logical field.

ROM having bit lines interlaced with column lines and cell column

A differential amplifier (10) has two input terminals (16,18), an output terminal (20) together with power terminals (12,14). The differential amplifier comprises two or more stages with each stage having a pull-up transistor (22) and a pull-down transistor (26). The first input terminal (16) is connected to alternate stages of the amplifier (10) and the second input terminal (18) is connected to the remaining alternate stages of the amplifier (10). The gain of the various stages is determined by fabrication of the transistors, in particular, the geometries of the transistor channels. A state transition at an output terminal (20) is produced when the voltages at the input terminals (16,18) are approximately equal and the gains of the various stages are essentially equal. A state change at the output terminal (20) is caused to occur when there is a given voltage offset between the voltages at the input terminal (16,18) when the gains of the two sets of alternate stages of the amplifier (10) are made unequal.

FET differential amplifier

The voltage gain of an MOS transistor inverter stage is made independent of the device threshold voltages and of channel lengths by making the length and width of the channel region of the upper load transistor equal to the length and width of the channel region of the lower driver transistor.

MOS transistor circuits having matched channel width and length

An error-correction circuit for correcting up to one error in an M-bit data field having the conventional number K parity bits associated with it uses a syndrome word having K-1 bits. The data elements are ordered sequentially and the K-1 bit syndrome word points to errors in the data only, not to errors in the parity bits. One of the data addresses in the field is reserved as a no-error flag and a Kth parity check bit associated with the syndrome word flags an error in the parity bits.

Error-correcting circuit having a reduced syndrome word

A sub-circuit for discharging a relatively high voltage node in an integrated circuit includes an enhancement transistor connected between ground and an intermediate node and a depletion transistor connected between the intermediate node and the high voltage node, both of the transistors having the same gate voltage.

Circuit for discharging bootstrapped nodes in integrated circuits with

A test circuit (10) for a semiconductor memory is provided. The semiconductor memory includes a redundant decoder (70) for receiving memory address signals (66, 68) which is connected to a redundant circuit element via a signal line (72). The redundant decoder (70) can be programmed in accordance with the address of a defective circuit element, such that when the decoder (70) is addressed by the memory address signals (66, 68) the decoder (70) selects a predetermined redundant circuit element. The test circuit (10) generates an output signal (14) indicating that the circuit element selected by the decoder (70) is a redundant circuit element. The output signal (14) is applied to an indicator circuit (16) which is enabled in a test mode by an abnormal condition detector (26). The output (18) of indicator circuit (16) is applied to an external pin (20).

Semiconductor memory redundant element identification circuit

A dynamic load circuit (34) selectively applies a high voltage state to a circuit node (42). A clock signal is coupled to a first node (54) and the inverse of the clock signal is coupled to a second node (60). Isolation transistors (50, 70) are controlled by the voltage level at the circuit node (42) to isolate the clock signals from the first and second nodes (54, 60) when the circuit node (42) is at a low voltage state. A high voltage signal V.sub.pp is coupled through a transistor (58) to the first node (54). The voltage at the first node (54) is coupled through a transistor (56) to the circuit node (42). The circuit node (42) is further coupled through transistors (62, 64) to the second node (60). The application of the alternating positive transistions of the clock and inverse clock signal cause the circuit (34) to apply a progressively increasing voltage to the circuit node (42). The dynamic load circuit (34) functions even if the threshold voltages of the high voltage transistors therein are almost as high as the supply voltage.

MOS dynamic load circuit for switching high voltages and adapted for use

A method and apparatus is described for initiating a selected functional mode for a semiconductor memory circuit to determine the implementation of redundant elements in a semiconductor memory. The method for initiating the selected functional mode comprises applying an active state of at least a first of the operational signals to the memory circuit followed by applying an active state of a second of the operational signals to the memory circuit. The timing of the second operational signal relative to the first operational signal is not within the defined specification limits of the first and the second operational signals for conventional data transfer to and from the memory. An example of the selected functional mode is the activation of circuitry (62) which serves to apply a predetermined data state to a redundant column (63) which can be substituted to replace a defective primary column within a memory array. After the memory array has previously received a first data state and the circuit (62) is activated to apply a second data state to the redundant column (63) the memory array is read and each column which produces a second data state is determined to be a redundant column. With knowledge of the column substitution algorithm, it can then be determined which of the redundant columns have been programmed to replace specific original columns. This method can therefore determine the physical configuration of the memory circuit despite the incorporation of redundant elements into the primary memory array.

Testing and evaluation of a semiconductor memory containing redundant

A nonvolatile random access memory cell (10) includes a static random access memory circuit and a corresponding nonvolatile memory circuit. The volatile memory circuit operates in a conventional manner and has first and second data states. Upon receipt of a store command signal a charge storage node is driven to either a first or a second charge state, depending upon the data state in the volatile memory circuit. For one charge state the charge storage signal is gated through a transistor (64) and a capacitor (68) to a floating gate node (44). Charge is transferred to and from the floating gate node (44) through current tunneling elements (48,50) which comprise a dielectric fabricated on a monocrystalline substrate. For the recall operation a recall command signal is applied to a transistor (52) which couples a transistor (42) to the DATA node (22) of the volatile memory circuit. If a positive charge state has been stored at the charge storage node (44) the transistor (42) is rendered conductive to pull the DATA node (22) to ground to restore the data state to the volatile memory circuit. If a negative charge state has been stored at the charge storage node (44) there is no load applied to either the DATA node (20) or the DATA node (22). The cross-couple transistors, (12,14) are fabricated to have different lengths such that the node (22) is driven to a high voltage state whenever a default condition is encountered, thereby restoring the original data state to the volatile memory circuit.

MOS Random access memory cell with nonvolatile storage

A dynamic random access memory (10) is fabricated on a substrate (12) and is divided into memory sections (14, 16). Memory cells (46) are connected to bit lines (18-28, a and b), which are organized into pairs that are connected to respective sense amplifiers (34-44). A row clock circuit (52) generates clock signals to enable the addressed word line. Additional clock signals are generated by other clock circuits (56, 58). A charge pump circuit (78, 80) produces a substrate bias and includes a free running oscillator. The signal generation circuits (52, 56, 58, 78, 80) produce signal transitions which are coupled by parasitic capacitors (66-76, 81-88) into the bit lines (18-28, a and b). The clock circuits are fabricated in a symmetrical placement in relation to the bit lines (18-28, a and b) and sense amplifiers (34-44) such that the transient signals capacitively coupled from the clock circuits into the bit lines have a very low differential mode amplitude. The reduced differential mode interference from the clock circuits permits the sense amplifiers (34-44) to more accurately read the states of the memory cells (46).

Placement of clock circuits for semiconductor memory

A semiconductor memory circuit (140) includes a plurality of memory cells each having an access transistor (154, 158) and a storage capacitor (162, 166). The memory cells are connected to digit lines (142, 144) each of which is split into halves each connected to one input of a sense amplifier (146, 148). The sense amplifiers (146, 148) operate to pull one of the half digit lines connected thereto to ground while a pull up circuit (220) operates to elevate the other half digit line to the supply voltage. A margin test circuit receives through a control pin (236) an externally supplied test command which generates a test signal (318) to generate marginal low and marginal high voltage states to be written into the memory cells. The marginal low voltage state is generated by a voltage divider (288). The marginal high voltage state is generated by disabling the pull up circuit (220). To prevent loss of the marginal low state the sense amplifiers (146, 148 and 248) are disabled by the internally generated test signal. While the externally supplied test command is applied to the semiconductor memory circuit (140) marginal voltage states are applied to memory cells in accordance with externally supplied address and operational commands. The marginal voltage states are utilized to simplify testing of the circuit.

GO/NO GO margin test circuit for semiconductor memory

A dynamic random access memory cell (30) includes an access transistor (32) having the gate terminal thereof connected to a word line (34) and the source and drain terminals thereof connected between a bit line (36) and a node (37). A charge storage capacitor (38) is connected between the node (37) and a decoded plate line (40). The plate line (40) receives a bi-level voltage which shifts levels in a timing sequence keyed to the word line (34) signal. Shifting of voltage levels provided to the capacitor (38) through the plate line (40) essentially doubles the signal margin of the memory circuit (30) to thereby enhance the reliability of the data stored in the memory circuit (30).

Dynamic random access memory cell with increased signal margin

A dynamic random access read/write memory having 4,096 binary storage cells is disclosed. The system utilizes a single set of six address input buffers and one decoder for both row and column address information. The memory array includes two 32.times.64 arrays of dynamic storage cells separated by a row of 64 sense amplifiers each having split sense buses or digit lines extending to each column of memory bits. The decoders are disposed along one edge of the array which is at right angles to the row of sense amplifiers. The column enable lines from the decoders extend through the memory array between parallel row enable lines and then turn and proceed as a different level of interconnect between parallel digit lines to select the addressed sense amplifiers. Each column enable line enables two sense amplifiers which simultaneously read data from two cells of the addressed row. The least significant bit of the six column address inputs is used to make the final one out of two selection of the sense amplifier and thus the cell from which data is to be read or in which data is to be written. The decoder includes circuit means for storing the decode signal identifying a selected row while subsequent column address signals are input to the chip and decoded by the same decoder. Row address data is first input through the six address pins to the chip; the six inputs are sampled and latched in six address buffers; and the six address inputs are then decoded so that a single row enable line is selected and held active dynamically. Then while data is read from all storage cells in the active row by the sense amplifiers, column address signals applied to the same input pins for the chip are sampled and latched in the same six address buffers, and decoded by the same decoder to select and hold a column enable line active.

Growing community of inventors

Dallas, TX, United States of America

Robert J Proebsting