Abstract: An electrically erasable programmable memory cell of the four transistor type in which a floating gate transistor has one end of its source to drain path coupled to the write line and the other end to the read line through a read switch. Its control gate is connected to the sense line. A tunnel device has a cathode connected to the floating gate of the floating gate transistor, and an anode through a write switch connected to the write line. The gates of both the read and write select transistors are connected to the row line. By coupling one end of the read switch to the read line rather than connecting one end of the source to drain path of the floating gate transistor to the read line for unselected cells in which the read switch is off, only the capacitance of one end of the read switch is added to the parasitic capacitance of the read line whether the floating gate of the floating gate transistor has previously been charged negatively or positively.
Abstract: A single-chip microprocessor device of the MOS/LSI type contains an ALU, several interal busses, a number of address/data registers, and an instruction register with associated control decode or microcontrol generator circuitry. The device communicates with external memory and peripherals by a bidirectional multiplexed address/data bus and a number of control lines. The ALU, registers and busses along with the control ROM are constructed in an interrelated layout whereby minimum space is needed on the chip. Like bits in all registers and the ALU are aligned and in a regular pattern. The busses are metal lines overlying each of the strips of ALU/register bits. Controls are polysilicon lines perpendicular to the busses and aligned with columns of the control ROM. The control ROM is an array of rows and columns of potential MOS transistors, compressed by eliminating column lines which contain no transistors.
Abstract: An input protection circuit for an MOS device uses a thick-oxide transistor connected as a diode between a metal bonding pad and ground. The channel width of this transistor is chosen to be sufficient to withstand large, short-duration current spikes caused by electrostatic discharge. More important, the spacing between a metal-to-silicon contact to the drain of this transistor and the channel of the transistor (where heat is generated), is chosen to be much larger than usual so the metal of the contact will not be melted by heat propagating along the silicon surface during the current spike due to ESD. This spacing feature also applies to circuits for output pads, or circuits using diode protection devices.
Abstract: A decoder and driver circuit for producing an output voltage exceeding the power supply uses a CMOS decode circuit followed by NMOS output stage and pump circuit. The pump clock is derived from a controlled oscillator, and the oscillator is synchronized with the access cycle of the memory device in which the circuit is used, so retention of the high level output is assured for an indefinitely long cycle time.
Abstract: A redundant column circuit includes a row shared predecoder (12) and predecoders (16), (18) and (20). The predecoders (16-20) are input to a one-of-sixty-four decoder (28) for providing sixty-four decoded outputs therefrom, each of which is input to a one-of-four multiplexer (30). Each of the multiplexers (30) selects one of four normal decode outputs and one of four redundant decode outputs. The selected decode output is determined by the four outputs from the row shared predecoder (12). A switch bank (32) of single pole double throw switches selects between a normal and a redundant output with the redundant output having the address associated therewith incremented by one. The output of the switches in the bank (32) is input to the deactivation circuits (36) for output therefrom to a memory array (38). The memory array (38) has a redundant column (R) in parallel therewith which is controlled by the first switch in the switch bank (32).
Abstract: In video computer system having a dual-port bit-mapped RAM unit incorporating a shift register, provision is made for coupling data between column lines and the shift register, and for simultaneously preventing any column line from being coupled with the random data output terminal of the RAM unit. Accordingly, this prevents two or more different data bits from appearing simultaneously from the RAM unit and causing confusion as to which is the valid signal and which is a spurious signal.
Abstract: A self testing ROM includes an information array (10) for storing data therein and a parity array (12) for storing associated parity information for each of the data words. The data is accessed and multiplexed for input to a block code error detect circuit (30) for detecting the error and outputting an error syndrome on a bus (32). The error syndrome is input to an error correct circuit (34) for correction of the accessed data during a first pass through the error detect circuit (30). This corrected data is then input to latches (39) and (41). The latched data is then input back to the block code error detect circuit (30) during a second pass to determine if the data was corrected. If not, this indicates that there were too many errors to be corrected by the error detection algorithm. This is detected with a system error detect circuit (43) during the second pass through the block code error detect circuit (30).
Abstract: In a video computer system having a RAM chip with a shift register connected to its serial output terminal and actuated by a first clock circuit, a second different clock circuit is included to cause the data bit in the first stage of the register to also appear at the serial output terminal of the chip. Accordingly, signals from the first clock circuit will then sequentially transfer data bits from the shift register, to the output terminal of the RAM chip, without omitting or losing a clock cycle, or a portion thereof.
December 30, 1983
Date of Patent:
August 18, 1987
Texas Instruments Incorporated
Mark F. Novak, Karl M. Guttag, Donald J. Redwine
Abstract: Adjustment of operating parameters for a functional circuit is provided by fuse links (44) and (45). For a DRAM, the fuse links (44) control the various internal delays of a timing control generator (40) and fuse links (45) control the sensitivity of sense amplifiers by controlling an access control circuit (42). The sense amplifiers (14) determine the access parameters for a plurality of memory cell arrays (10) and (12). By varying the parameters of the sense amplifiers, the access parameters can be controlled by one adjustment on the central control circuitry.
Abstract: A semiconductor dynamic memory device has an array of one-transistor cells, with row and column decode to produce a 4-bit wide input or output from the array. Single-bit data-in and data-out terminals for the device are coupled to the 4-bit array input/output in a sequential mode. The row and column addresses are latched when RAS and CAS drop, and the latched address includes the address of the starting bit within the 4-bit sequence for serial I/O. The other three bits follow as CAS is cycled. This starting address is used to set a bit in a 4-bit ring counter, which is then used to cycle through the sequence. To reduce power dissipation, the inverter stages of the ring counter are operated by pulsed clocks generated from the asynchronous memory control clocks received from the CPU.
Abstract: A semiconductor memory is comprised of four arrays (10), (12), (14) and (16) that have the memory elements therein arranged in accordance with pixel positions on a display. The memory arrays have associated shift registers (34), (36), (38) and (40) which have data loaded in parallel and output in a serial format to the display. Each of the shift registers can be connected in a circulating fashion or a shift register of adjacent arrays can be cascaded. Switches (56), (58), (60) and (62) are provided for configuring the shift registers for either circulation or cascading of data. In the circulating mode, the input and output of the shift registers is multiplexed on one pin whereas in the cascaded configuration, one array receives a dedicated serial input and the other array in the cascaded pair outputs the serial output on a dedicated pin.
Abstract: A semiconductor device such as a dynamic read/write memory or the like is made by a twin-well CMOS process that employs a minimum number of photomasks. Field oxide isolation areas are formed in nitride-framed recesses so a relatively plane surface is provided, and a minimum of encroachment occurs. Both P-channel and N-channel transistors are constructed with silicided, ion-implanted, source/drain regions, self-aligned to the gates, employing an implant after sidewall oxide is in place, providing lightly-doped drains. The threshold voltages of the P-channel and N-channel transistors are established by the tank implants rather than by separate ion-implant steps for threshold adjust.
November 29, 1984
Date of Patent:
July 7, 1987
Texas Instruments Incorporated
Robert R. Doering, Michael P. Duane, Gregory J. Armstrong
Abstract: A digital data processing system employs a single-chip microcomputer device having separate on-chip program and data memory, executing instructions in a single machine state. An external program address bus allows off-chip program fetch in a memory expansion mode, with the opcode returned by an external data bus, or all program storage can be off-chip in a system emulator mode. The ALU and accumulator have 32-bit data paths, while the busses are 16-bit. Various test modes are permitted; for example, the internal program ROM may be read out on the data bus, one opcode at a time, for test purposes without executing the opcodes.
Abstract: In manufacture of VLSI semiconductor devices, the insulator surface upon which a metallization pattern is deposited is made more smooth by the deposition of a thin insulator in liquid form. This insulator may be silicon oxide deposited from a solution, or otherwise from a liquid carrier, spun on to create thick portions in corners and steep edges, thus promoting improved step coverage. The insulator may be phosphorous-doped so the subsequently-applied thick oxide may be undoped, permitting a two-step wet/dry etch for contact holes, producing sloping sides to reduce metal thinning.
Abstract: A metal gate and contact/interconnect system for MOS VLSI devices employs a multiple-level refractory metal structure including a thin layer of molybdenum for adhesion to oxide and a thicker layer of tungsten over the molybdenum. The metal gate is encapsulated in oxide during a self-aligned siliciding operation. A contact to the silicide-clad source/drain region includes a thin tungsten layer, then the molybdenum/tungstem stack, and a top layer of gold.
Abstract: A semiconductor integrated circuit, such as a high-density, dynamic read/write memory containing an array of rows and columns of memory cells, is constructed to allow high speed testing to identify row line faults in one example, and to identify column or sense amplifier faults in another example. Row lines for the array in a dynamic RAM may contain detector circuits activated in a special test mode to produce a data output indicating integrity of each row line without requiring the access of the cells in the array in complex data patterns. The connection between bit lines in the array and sense amplifiers may be shifted or transposed in another embodiment to distinguish between column or sense amplifier faults; this construction also allows rapid loading of test patterns.
Abstract: A semiconductor memory comprises four arrays (10), (12), (14) and (16) disposed on a single semiconductor chip. Each of the arrays has a serial shift register (86) associated therewith. Data is transferred from the bit lines of the associated array through a transfer gate (90) for storage in the shift register (86). A tap latch (88) is provided on the output of each of the shift bits in the shift register (86) for determining the output therefrom. The tap latch (88) stores a tap decode signal which is decoded from a tap address by the column decoder (30). The column decoder (30) also decodes the column address in the random mode. The tap decode signal selects any of the shift bits in the shift register (86).
Abstract: In a video computer system, an improved memory circuit is provided which is effective for delivering stored data only at appropriate instances, and which is also simpler and more reliable in design. In particular, the system preferably includes a bit-mapped RAM circuit which assumes a serial mode in response to both a row address signal and a suitable data output control signal, and which assumes a parallel or "random" mode when only the row address is received. Stored data is transferred to a parallel output terminal in the RAM circuit, or to a serial output terminal therein, depending upon the sequence of these signals as well as the column address and read signals, whereby the data output control signal is used for two separate and different purposes within the system.
Abstract: A register of the type used on as address counter in a dynamic RAM is tested by a method which does not require cycling through every possible value of the register contents. The counter is first loaded with a fixed value, all 1's or all 0's, and the contents checked by an AND or OR gate, producing a one-bit output which is monitored off-chip. Then, the carry feedback path to the counter register is altered, as by inverting all but the LSB, and the contents again checked, using the one-bit output via the AND or OR. In this manner, the operation of the counter is tested in three cycles.
Abstract: Metal-gate transistors with metal silicide cladding of the source/drain regions, as may be used in very high density dynamic RAM devices, are made by a process in which the metal gate is encapsulated in oxide and the cladding is self aligned with the encapsulated gate. A thin coating of a refractory metal is applied to the source/drain areas and heated to react with the exposed silicon. The unreacted metal is removed by an etchant that does not disturb the metal gate or the silicide.