Abstract: A dual-port semiconductor memory device is disclosed that includes a number of array blocks (12) having memory cells disposed in rows and local columns, with each local column having a local bit line pair (30). A sense amplifier row (28) is associated with each array block (12) and includes a sense amplifier (28) coupled to each local bit line pair (30). Each sense amplifier row (14) is commonly connected through a number of bit line gates (32) to global bit line pairs (26) disposed on a higher fabrication layer than that of the local bit lines (30). A block decode signal commonly activates all the bit line gates (32) of one array block to couple the global bit lines (26) to one sense amplifier row (14). The global bit lines (26) are also connected to a column decoding section (18) which provides random input/output selection of a global bit line pair (26). A latch row (20) is also coupled to the global bit lines ( 26) through a number of latch gates (42).

Abstract: A semiconductor random access memory (RAM) is disclosed having a number of array blocks (14), each array block (14) including standard rows, standard columns, redundant rows (24) and redundant columns (26). A row redundancy circuit (44) is provided for each array block that includes a single row fuse bank (28). Within the row fuse bank (28) are row disable fuses (42) and redundant row fuses (54) interspersed at regular intervals between the row disable fuses (42). Each row disable fuse (42) disables a standard row segment (32) when opened. A redundant row segment (46) is driven according to the combination of opened redundant row fuses (54). A column redundancy circuit (62) includes a number of column fuses (64) disposed in a column fuse bank (30). Redundant columns (26) are enabled by opening selected ones of the column fuses (64). If a redundant column (26) is driven the remaining standard columns of its associated array block (14) are disabled.

Abstract: A pre-sense amplifier (10) is disclosed. The pre-sense amplifier (10) increases a low-going bit line signal from a cell column (24) by an amount approximately equal to the threshold voltage of an n-channel MOS transistor. The pre-sense amplifier (10) includes a first channel (12) and a second channel (14), each channel having a precharge/transfer transistor (16) and an output precharge transistor (18). The output precharge transistors (18) are clocked to pull the inputs to a sense amplifier (26) to a positive supply voltage. At the same time, the precharge/transfer transistors (16) precharge the bit lines of a cell column (24) to a voltage equal to the positive supply voltage less their threshold voltage. When the cell column (24) pulls one of the bit lines low, the corresponding precharge/transfer transistor (16) connects the bit line with the sense amplifier input, redistributing the charge across the bit line capacitance and the sense amplifier input capacitance.

Abstract: An improved redundancy scheme for monolithic memory devices is disclosed. A memory device (10) has a quadrant array (12) of main memory quadrants (14). Each main memory quadrant (14) includes a number of memory cells arranged in a number of main memory rows (26) and main memory columns (28). A first level of redundancy is provided within each main memory quadrants (14) which has local redundant rows (36) and local redundant columns (38) for replacing defective cells therein. A second level redundancy is provided by redundant memory sections (20) which are used in combination to replace main memory quadrants (14) if necessary. The redundant memory sections (20) are disposed along the edge of the quadrant array (12). A third level of redundancy is provided by redundant section rows (52) and redundant section columns (54) within each redundant memory section (20) to replace defective cells therein.

Abstract: An address transition detection (ATD) circuit provides an address transition detection pulse in response to either a high-to-low or low-to-high external address transition. The ATD circuit includes an address buffer that translates an externally applied address signal into an internal address signal and its logical complement. Two delay chains, each of which includes inverters, capacitors, a NAND gate and a CMOS pass gate, combine with the address buffer and an n-channel pull-down transistor to provide the ATD circuit. The outputs of the CMOS pass-gates are connected to the gate of the pull-down transistor. The drain of the pull-down transistor serves as the local ATD node of a dual-load feed-back controlled ATD pulse generator. The ATD local node is common to address buffers that select memory cells within a particular memory block. Address buffers responsible for switching between blocks have separate feedback-controlled ATD pulse generators in order to optimize the access time of the memory device.

Abstract: Hierarchical redundancy is implemented in a monolithic memory by providing standard row and column redundancy augmented by redundant blocks, each having its own internal row and block redundancy. The efficiency of the redundant blocks is further enhanced by subdividing the redundant blocks into individually replaceable segments of rows or columns. A test and repair algorithm utilizing the hierarchical redundancy scheme is also provided.

Abstract: A memory array wherein transfer bus length is reduced and segmented by arranging the column decoder select signals to run across the length of the word line to reduce the node capacitance seen by the corresponding memory cell. This transfer of low capacitance from the transfer bus, i.e., the critical path, to the select line, which is a non-critical path for speed, improves access speed.

Abstract: An address detection transition circuit provides an address transition detection pulse in response to either a high-to-low or a low-to-high external address input logic transition. The address transition detection circuit includes an address input buffer that responds to the external address input by providing first and second complimentary signals at first and second address input buffer output nodes, respectively. A first delay chain connected between the first address input buffer output node and the buffer output node responds to a high-to-low external address input logic transition by providing a logic high signal at the buffer output node. Similarly, a second delay chain connected between the second address input buffer output node and the buffer output node responds to a low-to-high external address input logic transition by providing a logic high signal at the buffer output node.

Abstract: Methods and apparatus are provided for using a partially functional memory device with extra fail bits to create a fully functional monolithic device. The concept may be expanded for use in waferscale integration. The concept may also be used to create a fully functional memory board using partially functional memory chips. To accomplish this, a distinct fail bit array is added to each memory chip and the defective bits in the main chip are replaced by bits in the fail bit array using a programmable element, such as a programmable logic array (PLA). The PLA generates fail bit access addresses to locations in the fail bit memory that replace the defective bits in the main array. Thus, the external address is simultaneously applied to both the main array and to the PLA. If there is a match between the external address and an internal location in the PLA, the PLA outputs a flag and a fail bit address which are used to disable the main array access and to enable access to the fail bit memory.

Abstract: A differential latch sense amplifier circuit uses a differential amplifier to isolate the input signal nodes from the output driver nodes. The latch circuit provides the necessary speed and level shifting to drive the next stage. This, coupled with a tristate driver circuit, makes the zero power sense amplifier capable of driving large capacitances with tristatability.

Abstract: A boot-strapped decoder circuit in accordance with the present invention activates a selected word line output in response to an input address. The decoder circuit includes a plurality of row decoders, each of which has a plurality of word line outputs. The row decoders respond to a select signal that identifies one of the row decoders as a selected row decoder. The select signal is generated by a regular predecoder based on the most significant bits of the input address. Low order predecoder circuitry utilizes the least significant bits of the input address to generate a low order decoder signal. The selected row decoder includes boosting means coupled to each of the selected row decoder outputs and responsive to the low order predecode signal for generating a boot-strapped output voltage on a selected word line output of the selected row decoder.

Abstract: A semiconductor dynamic read/write memory of the multiplexed-address type employs an on-chip refresh counter which is activated by CAS-before-RAS sequence. This counter is made up of stages almost identical to the row address buffers so the same clocks can be used. Either the address input buffers or the refresh counter stages are gated into second-stage row address buffers, and carry feedback from these second stage buffers to the counter stages is used to increment the counter. The access time of the memory for normal read or write is not degraded by the refresh 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. Single-bit data-in and data-out terminals for the device may be 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 this includes the address of the starting bit within the 4-bit sequence. 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.

Abstract: A clock circuit for producing a high-level delayed clock output following an input clock employs an output transistor and pull-down transistor controlling an output node in response to the voltage on a drive node. The input clock is applied to this drive node by a decoupling arrangement, consisting of two series transistors. The first transistor isolates the input charge on a holding node, and the second of the series transistors transfers the charge to the drive node after the desired delay. The output node is held at zero until after the delay, with no unwanted voltage rise, and no d.c. power loss. A large capacitive load can be driven.

Abstract: In a clock generator circuit for a dynamic RAM or the like it is necessary to boot certain nodes to a value to above the supply voltage in order to provide a high-level gate voltage for output transistors. To prevent excess voltage on the gate oxide of a transistor connected to a booted node, a series transistor is added which has the supply voltage on its gate, so neither transistor will have the full booted voltage across its gate oxide.

Abstract: A dynamic read/write memory device constructed in a semiconductor chip of the MOS VLSI type employs an on-chip substrate bias generator which is sequentially clocked by the clocks used in operation of the memory. The impact ionization current associated with each clock operation is thus individually supplied, and when a clock is not used the substrate bias for this clock is not generated.