International Business Machines Corporation

James J Covino

Jose Roriz Sousa

Alan L Roberts

Roy Childs Flaker

Harold Pilo

Luigi Ternullo, Jr

Garrett Stephen Koch

John P Connor

Robert Dean Adams

George Maria Braceras

Kevin G Petrunich

Marcel J Robillard

Stuart J Hall

Richard E Hee

Luigi Termullo, Jr

Jose R Sousa

A structure and method for performing back-to-back read and write memory operations to a same DRAM bank comprising articulating between reading data on a first bank during successive first bank read cycles and writing data to a second bank during successive second bank write cycles, cycling between reading data on the second bank during successive second bank read cycles and writing data to the first bank during successive first bank write cycles, and performing a refresh cycle on the first and second bank, wherein the first bank write cycles lag the first bank read cycles, and wherein the second bank write cycles lag the second bank read cycles. Moreover, the read and write memory operations constantly swap between the read and write cycles and between the first and second bank.

DRAM-based separate I/O memory solution for communication applications

An apparatus for generated impedance matched output signals for an integrated circuit is disclosed. The apparatus includes a master true driver circuit, a master complement driver circuit and multiple clone output driver circuits. The master true driver circuit includes a first driver control, a first output driver, a first impedance matching resistor and a first load. The master complement driver circuit includes a second driver control, a second output driver, a second impedance matching resistor and a second load. The clone output driver circuits, which are substantially identical to each other, can produce impedance matched output signals to their respective substantially identical loads. Each of the clone output driver circuit includes a driver control, a first unity gain amplifier, a second unity gain amplifier and a load. The inputs to the first and second unity gain amplifiers are supplied by the master true circuit and the master complement circuit via the driver control.

Method and apparatus for generating impedance matched output signals for an integrated circuit device

A comparator and variable delay circuit are provided to maintain the tracking between data and echo clocks in a double data rate (DDR)RAM device. This is accomplished by providing a global data signal (dummy data signal) that tracks with the actual memory array data. This global data signal is compared to the timing of the RAM clock (CLOCK) to determine a delay time between the two by which the pipeline clocks (CLKRISE/CLKFALL) must be delayed. As a result, the pipeline clocks are pushed out as needed so that they always transition after the array data arrives at the output latch. Therefore, as cycle time decreases, both echo clocks and data are pushed out identically and maintain their required tracking.

Cycle independent data to echo clock tracking circuit

The disclosed invention provides a circuit and burn-in test method for semiconductor devices that increases the speed of burn-in tests. The present invention accomplishes this by causing each of the devices under test to be tested multiple times (from 2 to 32+ times) during each power cycle. By such multiple cycling of the unit under test, during the power cycle, the total test time is shortened. It has also been found that the devices tested in accordance with the present invention are more efficiently stressed and have a reliability greater than devices passing the prior art tests. In accordance with the invention, the memory or logic devices under test are provided with a respective clock means that will operate each of the devices under test through multiple (from 2 to 32+ times) write and read operations during each power cycle. Data coherency for each read operation is provided as is the inversion of data if any fail is recorded during a read operation. Accordingly, the present invention provides a burn-in test that more efficiently stresses semiconductor devices such as memory or logic units, by a factor of up to 32. The invention utilizes the internal clock of a semiconductor device by cycling that clock x times during the period of each external clock cycle in the burn-in test and simultaneously synchronizes these internal cycles with the test cycle, thereby providing coherent data for each internal cycle.

Efficient semiconductor burn-in circuit and method of operation

A memory array comprising a number of memory cells, a set path, a signal path, and at least one word line for transmitting a word line select signal to a row of the memory cells. The word line extends from a first driver end to a second end. The memory array further includes a dummy word line extending from the first driver end to a point between the first and second ends and back to the first end for transmitting a tracking signal responsive to the word line select signal. By folding the dummy word line in this manner, improved tracking of the set path with the signal path is achieved.

Folded dummy world line

An associated memory structure having a plurality of memories amenable for testing and a method of testing the memories is provided. First and second memories are formed, wherein data in the first memory provides a basis for at least a portion of the input to the second memory during functional operation of two memories. Preferably, an output latch for receiving the output test data from the first memory is provided. Means are provided for loading the first memory with data which is utilized as a basis for providing at least a portion of the input to the second memory. An access path from the output port of the first memory to the input port of the second memory allows use of the data in the first memory to generate at least a portion of the input to the second memory. The first memory is first tested independently of the second memory. Thereafter, the first memory is loaded with preconditioned data that is used as a basis for inputs to the second memory during testing of the second memory. The second memory is then tested by generating inputs to the first memory during testing of the second memory. Thus, outputs of the first memory constitute at least a portion of test data inputted to the second memory. A latch is provided to capture the output of the test data from the second memory.

Using one memory to supply addresses to an associated memory during

A structure and method of operation of a cache memory are provided. The cache memory is organized such that the data on a given line of any page of the main memory is stored on the same line of a page of the cache memory. Two address memories are provided, one containing the first eight bits of the virtual address of the page of the data in main memory and the second the entire real page address in main memory. When an address is asserted on the bus, the line component of the address causes each of those lines from the cache memory to read out to a multiplexor. At the same time, the eight bit component of the virtual address is compared in the first memory to the eight bits of each line stored in the first memory, and if a compare is made, the data on that line from that page of cache memory is read to the CPU. Also, the entire real address is compared in the second memory, and if a match does not occur, the data from the cache to the CPU is flagged as invalid data. A structure and method are also provided to determine if duplicate addresses exist in the second address memory.

Method and structure for accessing semi-associative cache memory using

A method and apparatus are provided for parallel addressing a CAM and a RAM, and also for using a single wordline to address the CAM and/or RAM. The CAM and RAM are addressed using a common wordline, and the common wordline is also used for writing to the CAM during a write cycle and strobing the CAM during a read cycle.

Method and apparatus for parallel addressing of CAMs and RAMs

Dynamic CMOS circuits are provided with improved noise immunity. These circuits comprise first and second stacked NFET devices connected respectively between ground and a first node. An input node is coupled to the first NFET device closest to ground and a clock node coupled to the second NFET device closest to the first node. A PFET device is connected between the input node and a node formed by the stacked NFET devices. The first NFET device and the PFET device form an inverter for receiving an input signal, the switch point of the inverter being adjustable by adjusting the PFET/NFET ratio of the inverter, thereby increasing the noise immunity of the circuit.

Dynamic CMOS circuits with noise immunity

A method and apparatus for evaluating a memory having memory elements and redundant memory elements for redundancy replacement. The redundant memory elements are tested to determine the number of good redundant memory elements. The memory elements are also tested to determine whether there are any failing memory elements. It is then determined whether a sufficient number of good redundant elements are available to replace the failing memory elements. If an insufficient number of redundant memory elements are available, the testing is stopped.

Method and apparatus for testing redundant word and bit lines in a

A truc/complement receiver driver circuit in which the input signals may be applied prior to a sysnchronous clock signal. The input signals are sensed and latched to generate complementary output signals. The generation of the output signals causes the receiver portion of the circuit to be automatically reset for the next cycle. The leading edge of the systemclock causes the circuit outputs to reset and enables the receiver circuit to be enabled for the next cycle. Multiplexed input receiver circuits allow the circuit to respond to a plurality of input signal sources.

Address buffer for synchronous system

A low power, high speed, multistage asynchronous logic circuit having an interlocked restore mechanism. A first logic circuit detects a valid input signal and drives an output to a second logic circuit. The second logic circuit receives inputs from the first logic circuit and drives a data ready signal back to the first logic circuit when it detects the output from the first logic circuit. The first logic circuit resets when it receives the data ready signal from the second logic circuit and it detects that its inputs have been reset.

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Montpelier, VT, United States of America

James J Covino