International Business Machines Corporation

Tai Anh Cao

Satyajit Dutta

Thanh D Trinh

Thai Q Nguyen

Lloyd Andre Walls

Douglas Hooker Bradley

Khanh Tuan Nguyen

Nandor G Thoma

Robert Alan Philhower

Hieu T Ngo

Stanley Everett Schuster

Sam Gat-Shang Chu

Byron Lee Krauter

Herbert I Stoller

Michael Thomas Vaden

Aquilur Rahman

Wai Yin Wong

Tom Tein-Cheng Chiu

Joseph J McGill Iv

An adder circuit for determining the sum of two operands including a set of PGK circuits, at least one tier of group circuits, and a carry generation circuit. The PGK circuits generate propagate, generate, and kill bits corresponding to at least a portion of the first and second operands. The group circuit receives propagate, generate, and kill bits from a plurality of the PGK circuits and produces a set of group propagate, generate, and kill values. The carry generation circuit receives a carry-in bit and the outputs of at least one of the group circuits and generates a carry-out bit representing the carry-out of the corresponding group. The PGK circuits, group circuits, and carry circuits may use CMOS transmission gates in lieu of conventional complementary pass-gate logic (CPL).

Circuit suitable for use in a carry lookahead adder

An encoding element () and a decoding arrangement () is included with each separate circuit () in a system () of circuits which must communicate digital signals with each other. The encoding devices () included with the separate circuits () cooperate to produce an encoded signal on a common transmission line or network () which interconnects the various circuits. The decoding arrangement () associated with each respective circuit receives the encoded signal appearing on the transmission line and decodes the encoded signal to reproduce or recreate the digital data signals transmitted from the other circuits in the system.

Circuit for facilitating simultaneous multi-directional transmission of multiple signals between multiple circuits using a single transmission line

For testing a device under test ('DUT') a test specification is converted in a computer system by a pin vector generator process, which includes generating test vectors. The DUT has numerous input pins and such a pin vector is for a signal to drive one such pin. The pin vectors are compressed and saved. Ones of the pin vectors are loaded, upon initialization of a test, into a pipeline having a series of memory stages and extending from the computer system to channel cards in a test head. The pipeline is operated in data transfer cycles, delivering W bits per cycle. The pin vectors are decompressed at the respective channel cards in decompressor read cycles. X bits are read per decompressor cycle, W being greater than X, so that the pipeline may perform its data transfer cycles less frequently than the decompressor performs its read cycles.

Method, apparatus and computer program product for high speed memory testing

A memory array includes a storage unit with a number of sections and decoders coupled to respective ones of the sections for decoding an N-bit address signal and responsively asserting a signal on one of the word lines selected by the address signal. Local clock buffers are coupled to respective ones of the decoders for receiving a clock signal and an address signal including M most-significant bits of the N-bit address signal and generating respective timing signals. The decoders receive the timing signal from their respective local clock buffers. Each decoder is operable to alternately precharge and evaluate the N-bit address signal responsive to phases of the timing signal. Each local clock buffer is operable, responsive to a state of the M bits of the address signal, for selecting between holding its timing signal in a deasserted state and enabling its timing signal to follow the clock signal.

Method and apparatus for reducing power consumption in a memory array with dynamic word line driver/decoders

An adder circuit is provided that generates the sum and sum complement (sum_) signals by constructing the logic in such a way that various levels of both N-type devices and P-type devices are both &ldquo;on&rdquo; at the same when that leg is to be open. The logic is then determined by another level and only one P or N type device is on at a given time. For carry and carry complement (carry_) signals a circuit is provided that is symmetrical with respect to P and N devices. The carry and carry_ signals are generated by inputting the complement signals to the same circuit used to generate the carry signal. The symmetrical P and N type devices are complementary in that associated devices are on or off with respect to each other. Both the carry and carry_ signals are concurrently output. The symmetric nature of the static, dual rail, simultaneous, sum and carry circuits will improve switching performance and minimize the floating body effect that can be found in silicon on insulator (SOI) devices.

Simultaneous dual rail static carry-save-adder circuit using silicon on insulator technology

Digital signals from a group of three or more circuits ( ) are used to create an encoded or combined signal on a common transmission line ( ). The encoded signal is then decoded at each different circuit to produce or recreate the digital signal asserted by each different circuit in the group. The encoded signal comprises a signal included in a set of unique signal values, with each signal in the set corresponding to a different combination of digital signals asserted by the group of circuits. Decoding the encoded signal at each circuit ( ) in the group involves comparing the encoded signal to a particular reference voltage from a set of reference voltages. A particular reference voltage used in this comparison may be selected using one or more digital signals already decoded from the encoded signal.

Method for facilitating simultaneous multi-directional transmission of multiple signals between multiple circuits using a single transmission line

A compressor circuit suitable for use in an arithmetic unit of a microprocessor includes a first stage, a second stage, a carry circuit, and a sum circuit. The first stage is configured to receive a set of four input signals. The first stage generates a first intermediate signal indicative of the XNOR of a first pair of the input signals and a second intermediate signal indicative of the XNOR of a second pair of the input signals. The second stage configured to receive at least a portion of the signals generated by the first stage. The second stage generates first and second control signals where the first control signal is indicative of the XNOR of the four input signals and the second control signal is the logical complement of the first signal. The carry circuit is configured to receive at least one of the control signals and further configured to generate a carry bit based at least in part on the state of the received control signal. The sum circuit is configured to receive at least one of the control signals and further configured to generate a sum bit based at least in part on the state of the received control signal. At least one of the first stage, second stage, sum circuit, and carry circuit include at least one CMOS transmission gate comprised of an n-channel transistor and a p-channel transistor having their source/drain terminals connected in parallel, wherein the p-channel transistor gate is driven by the logical complement of the n-channel transistor gate. In one embodiment, the first stage, second stage, carry circuit, and sum circuit are comprised primarily of such transmission gates to the exclusion of conventional CMOS complementary passgate logic.

4:2 compressor circuit for use in an arithmetic unit

A method for automatically running a plurality of interactive programs that are necessary to complete a VLSI design and verification is disclosed. Layout data is completed and saved. Multiple programs of the VLSI logic are launched using this data. The submission of design programs (jobs) operate as program &ldquo;states&rdquo; with each program state having data inputs, data outputs possibly receiving logic inputs and generating logic outputs. The data inputs and data outputs may be conditional in that they were generated from other program states that may not have executed error free. Logic routines generate the logic signals which are logic combinations of the generated logic outputs and these logic signals may be used to launch other program states. Once the method is started, a designer simply corrects errors that occur and then re-starts the design process. The method keeps unconditional outputs of program states and updates conditional outputs and the program states execute until the VLSI design and verification is completed.

VLSI layout design jobs scheduling method

A Schematic database defining a Schematic is checked and saved. Multiple programs affected by the Logic of the VLSI Schematic are launched along with a Checking program that extracts data related to the Logic of the VLSI Schematic design and other data that may be necessary but is not related to the Logic of the VLSI Schematic design. The Schematic design programs operate as executable program states with each program state having program data inputs and outputs and program logic inputs and outputs. Once the method is started, a designer simply corrects errors that occur and then restarts the Schematic design process. If changes in the Schematic database do not affect the Logic then Logic related programs states are stopped and programs for correcting non Logic related changes are run. Program output data may be conditional with errors or unconditional without errors depending on operational modes.

Scheduler for schematic related jobs

The present invention allows for the simultaneous transmission of two digital signals from one integrated circuit to another. The two digital signals are encoded utilizing a voltage divider circuit and are then transmitted by one transmission line to the second integrated circuit chip. The second integrated circuit chip decodes the first digital signal and then utilizes this decoded digital signal to further decode the second digital signal.

Circuitry for allowing two drivers to communicate with two receivers using one transmission line

An exclusive OR circuit (10) includes an input stage (11) and a control arrangement (12,13) for controlling an exclusive OR logical evaluation. The control arrangement includes a pre-charge stage (12) which responds to a first level clock signal to enable the desired exclusive OR logical evaluation. The input stage (11) is connected to receive a first input signal and a second input signal and is also connected to an evaluation node (23). When the logic state of one input signal is unequal to the logic state of the other input signal, the input stage (11) couples the evaluation node (23) to ground. An output stage (13) of the control arrangement inverts the signal at an internal node (24) to produce the output from the exclusive OR circuit. A pre-charge stage (12) couples the internal node (24) to the evaluation node (23) only in response to a 'high' clock signal. Coupling the internal node (24) and evaluation node (23) allows the internal node to follow the state of the evaluation node and produce the desired exclusive OR evaluation through the output stage (13).

Clock controlled exclusive or circuit

A voltage converter circuit (10) includes a primary P-type FET (20) having its source-drain conduction path connected between an input (22) and a first output node (23). An N-type FET (21) is connected in parallel with the primary P-type device (20) between the input (22) and first output node (23). The gate electrode of the primary P-type device (20) is connected to the first output node (23) while the gate electrode of the N-type device (21) is connected to a second voltage supply at the voltage level of a desired second voltage signal. A first digital signal at a first voltage level is applied to the input (22). The voltage produced at the first output node (23) equals the desired second voltage level and comprises the input signal voltage reduced by the threshold voltage of the primary P-type device (20). One or more additional P-type devices (40) may be connected in series with the primary P-type device (20) to reduce the output voltage level further.

Voltage conversion circuit and method

Circuitry for allowing two drivers to communicate with two receivers

The present invention provides a driver/receiver pair connected as a repeater circuit which simultaneously transmits and receives information on multiple connected transmission lines. Transceiver circuits are provided which are mirror images of one another to perform the repeater function of the present invention. Each transceiver in the repeater circuit includes a non-inverting buffer stage which produces a signal swing less than the typical Vdd to ground which is typical for common CMOS inverters. The limited swing provides a variable reference input to a differential receiver element. This receiver looks at the incoming signal, and the signal being transmitted from the repeater to determine if the incoming signal is logical '1' or logical '0'. This is done on each side of the repeater since the actual voltage level on the wire at the repeater terminal is a composite of the signal received by the repeater and the signal being transmitted by the repeater. By using the repeater, the data rate is doubled and the transmission distance is increased when compared to simplex unidirectional operation.

Simultaneous transmission bidirectional repeater and initialization

The present invention allows for the simultaneous transmission of three digital signals from one integrated circuit to another. The three digital signals are encoded utilizing series resistors of predetermined values and are then transmitted by one transmission line to the second integrated circuit chip. The second integrated circuit chip decodes the first digital signal and then utilizes this decoded first digital signal to further decode the second digital signal, and then utilizes the decoded first and second digital signals to decode the third digital signal.

Growing community of inventors

Austin, TX, United States of America

Tai Anh Cao