Abstract: A system and method processor testing using test pattern re-execution is presented. A processor re-executes test patterns using different timing scenarios in order to reduce test pattern build time and increase system test coverage. The invention described herein varies initial states of a processor's memory (cache, TLB, SLB, etc.) that, in turn, varies the timing scenarios when re-executing test patterns. By re-executing the test patterns instead of rebuilding new test patterns, verification quality is improved since more time is available for execution, verification and validation. In addition, since the test patterns result in the same final state, the invention described herein also simplifies error checking.

Abstract: A system and method for pseudo-randomly allocating page table memory for test pattern instructions to produce complex test scenarios during processor execution is presented. The invention described herein distributes page table memory across processors and across multiple test patterns, such as when a processor executes “n” test patterns. In addition, the page table memory is allocated using a “true” sharing mode or a “false” sharing mode. The false sharing mode provides flexibility of performing error detection checks on the test pattern results. In addition, since a processor comprises sub units such as a cache, a TLB (translation look aside buffer), an SLB (segment look aside buffer), an MMU (memory management unit), and data/instruction pre-fetch engines, the test patterns effectively use the page table memory to test each of the sub units.

Abstract: An integrated circuit (IC) arrangement (10) comprises an integrated circuit (100) having a digital circuit portion (120) with a plurality of digital outputs (122), each of the outputs being arranged to provide a test result in a test mode of the integrated circuit (100). The arrangement (10) further comprises space compaction logic (140) comprising a space compaction network (160) having a plurality of compaction domains (162), each domain being arranged to compact a plurality of test results into a further test result, and a spreading network (150) coupled between the plurality of digital outputs (122, 210) and the space compaction network (160), the spreading network being arranged to duplicate each test result from the digital outputs (122,210) to a number of compaction domains (162).

Abstract: A method for testing functional boundary logic at an asynchronous clock boundary of an integrated circuit device is provided. With the method, each clock domain has its own scan paths that do not cross domain boundaries. By eliminating the scanning across the boundaries, the requirement to have two clock grids in the asynchronously clocked domains may be eliminated. As a result, circuit area and design time with regard to the clock distribution design are reduced. In addition, removing the second clock grid, i.e. the high speed core or system clock, in the asynchronously clocked domains removes the requirement to have a multiplexing scheme for selection of clocking signals in the asynchronous domain. In addition to the above, the system and method provide boundary built-in-self-test logic for testing the functional crossing logic of boundaries between the clock domains in a functional mode of operation.

Abstract: The present invention provides an apparatus and a computer program product for applying external clock and data patterns for TTP-LBIST. A simulation model for the logic under test is set up in a simulator. Next, a user sets up an external LBIST block, which comprises pre-verified internal clock and data pattern logic, and connects this block to the logic in the simulation model. The internal clock and data pattern logic provides the input patterns used in OPCG modes of LBIST. This internal clock and data pattern logic is already verified through the design effort. Therefore, the internal pattern generators become the external pattern generators in the simulation model. The external LBIST block applies the external clock and data patterns, and subsequently, the user receives and processes these output patterns to determine if the logic operates correctly.

Abstract: To further develop a circuit arrangement (100; 100?), and in particular an application circuit, that is arranged to generate at least one test pattern, and a method of testing and/or diagnosing the circuit arrangement (100; 100?) in such a way that reliable fault detection is ensured, it is proposed that the test pattern be remodelable and/or extendable into at least one presettable and/or deterministic test vector by means of at least one test pattern remodeling/extending element (10, 12, 14; 10?, 12?, 14?, and in that—the at least one test pattern remodeling/extending element (10, 12, 14; 10?, 12?, 14?) is arranged, and in particular is inserted, upstream of at least one, and in particular upstream of each, branch point (52, 54, 56) on the at least one signal path (50).

Abstract: A method of generating digital test patterns for testing a number of wiring interconnects is described. A first set of test patterns is generated; the number of test patterns in the first set is related to said number of wiring interconnects, and defines a first set of code words. From the first set of code words, a second set of code words is selected. The number of code words in the second set is equal to said number of wiring interconnects, and the selection of the second set of code words is such that the sum of the transition counts for the code words in the second set is minimized.

Abstract: A method, apparatus and computer program product are provided for implementing deterministic based broken scan chain diagnostics. A deterministic test pattern is generated and is loaded into each scan chain in the device under test using lateral insertion via system data ports applying system clocks. Then each scan chain is unloaded and a last switching latch is identified. The testing steps are repeated a selected number of times. Then checking for consistent results is performed. When consistent results are identified, then the identified last switching latch is sent to a Physical Failure Analysis system.

Abstract: A test circuit is capable of simultaneously performing various test modes. The test circuit includes a concurrent test mode controller for providing a plurality of decoding signals by receiving test mode input signals while test modes are being activated, and simultaneously providing the decoding signals if predetermined concurrent test mode signals are received.

Abstract: A pattern generator includes a main memory for storing a plurality of sequence data blocks for generating a test pattern, a first sequence cache memory for sequentially storing the sequence data blocks, a second sequence cache memory, a data development section for sequentially executing the sequence data blocks stored in the first cache memory and generating a test pattern and a read-ahead means, when the data development section detects a read-ahead instruction on reading ahead the other sequence blocks during executing one sequence data block, for reading the other sequence blocks from the main memory and storing the same in the second sequence cache memory.

Abstract: A tester and method are provided for testing semiconductor devices. Generally, the tester includes a multitasking Algorithmic Pattern Generator (APG) to concurrently execute multiple programs on multiple test sites using a single pattern generator. In one embodiment, up to eight test programs are run independently and concurrently on eight independent sixteen-pin devices on a 128 pin test site. When the multitasking APG is ready to broadcast to a device, timing system associated with that device only (and not the other devices) are loaded. While the timing system is executing the cycle of the test programs for the device just loaded, the APG continues on to load the other devices. Because of the slow cycle rates required for programming versus reading, the tester is particularly advantageous for testing flash memory. Optionally, for higher throughput, the APG can be run in lock step at up to a maximum operating frequency of the APG during read cycle of flash.

Abstract: Integrated circuit bus integrity may be verified without specialized test equipment. In a diagnostic mode, the integrated circuit may output a series of predetermined activation patterns onto the data bus to verify integrity of the data bus. Further bus verification may be provided by an address capture mode where address bus contents are reflected onto the data bus. A microprocessor may control diagnostic mode operation.

Abstract: A method and system for evaluating performance of a device by on-chip determination of BER may include establishing and generating PRBS test packets in a closed communication path internally within a physical layer device (PLD) and a remote PLD. A BER for the PLD may be determined from within the PLD based on a comparison of at least a portion of the generated test packets with at least a portion of the generated test packets transmitted over the closed communication path received by the PLD via the closed communication path from the remote PLD. A transmit path of the PLD may be internally coupled to a receive path of the PLD, and a receive path of the PLD may be internally coupled to a transmit path of the PLD. The PLD may be internally configured to operate in an internal optical loopback mode or an internal electrical loopback mode.

Abstract: A signal generator generates a WiMedia ultra wideband test signal with a user interface for setting test sequences and parameters of the test signal. Parameters are set for Presentation Protocol Data Units associated with Packet Groups of the test signal. A signal processing unit compiles the Groups containing the Presentation Protocol Data units to generate digital data representative of the test signal. A waveform generator receives the digital data and generating a test signal output having Packet Groups containing Presentation Protocol Data Units. A method is describes for setting test sequences and parameters of an ultra wideband test signal test signal with a user interface of the signal generator.

Abstract: A semiconductor integrated circuit (LSI) in which control information for determining a voltage or a width of a pulse produced itself can easily be set in parallel with other LSIs, and set information can be corrected easily. From an external evaluation device, a voltage of an expected value is supplied in overlapping manner to a plurality of LSIs each having a CPU and a flash memory. Each LSI incorporates a comparison circuit comparing an expected voltage value and a boosted voltage generated in itself. The CPU refers to a comparison result and optimizes control data in a data register for changing a boosted voltage. The CPU controls the comparison circuit and the data register and performs trimming in a self-completion manner, thereby making, trimming on a plurality of LSIs easily in a parallel manner and a total test time reduced.

Abstract: According to one embodiment, a built-in self test (IBIST) architecture/methodology is disclosed. The IBIST provides for testing the functionality of an interconnect (such as a bus) between a transmitter and a receiver component. The IBIST architecture includes a pattern generator and a pattern checker. The pattern checker operates to compare a received plurality of bits (for the pattern generator) with a previously stored plurality of bits.

Abstract: A method for testing semiconductor chips is disclosed. In one embodiment, a chip to be tested which has a test logic, at least one test mode is set, the test modes are executed in the chip and test results or the status of the test modes are output from the chip. The method includes providing a chip having at least one first register set having a plurality of registers and at least one second register set having a plurality of registers, at least one register of the first register set and at least one register of the second register set being 1:1 logically combined with one another. A first serial bit string is stored, the bit sequence of which can be assigned to at least one test mode, in the first register set. A bit sequence is transmitted for application of the logical combination between the first register set and the second register set to the first bit string stored in the first register set. The test results are read out by means of a serial second bit string.

Abstract: A test device includes: the first reference clock generation unit for generating the first reference clock; the first test rate generation unit for generating the first test rate clock based on the first reference clock; the first driver unit for supplying the first test pattern to an electronic device based on the first test rate clock; the second reference clock generation unit for generating the second reference clock; the first phase synchronization unit for synchronizing the phase of the second reference clock with the phase of the first test rate clock; the second test rate generation unit for generating the second test rate clock based on the second reference clock having the synchronized phase; and the second driver unit for supplying the second test pattern to the electronic device based on the second test rate clock.

Abstract: The present invention is directed to a system and method for quality improvement by identifying test patterns for DFT logic faults and functional logic faults. The identified test patterns may be selectively utilized for pruning of patterns or DPM estimation. Functional faults and DFT faults may be identified from detected TDF faults. The functional faults are faults on a logic which was present in a pre-test insertion net list. Remaining faults are the DFT faults. A set of test patterns for DFT faults may be utilized as the first target for the pattern truncation which will reduce the amount of test patterns to be tested. A set of test patterns for functional may be utilized for improving the TDF coverage.

Abstract: Apparatus and method for testing a CDMA integrated circuit including a demodulator for correlating input data with one of a set of codes and a test data pattern generator for spreading input test data with one of the set of codes to form a spread test data and providing the spread test data to the demodulator. The set of codes may be combined with the input test data to generate a set of spread test data which are then fed to the various components of the CDMA chip for testing the various components. In one embodiment, each one of the set of codes comprises a scrambling code and a spreading code.

Abstract: Constraining sequential data expressing sequential data which a sequential pattern to be extracted must include is specified in advance. Sequential pattern candidates with sequence length 1 are initially determined from among a plurality of input sequential data. Next, a set of sequential pattern candidates is generated by determining a plurality of new sequential pattern candidates by elongating the sequence length of the sequential pattern candidates. In this sequential pattern candidate set, after sequential pattern candidates which can generate only a sequential pattern which does not include constraining sequential data are eliminated, sequential data which include constraining data, and frequently appear are extracted as a new sequential pattern.

Abstract: Estimating the difficulty level of a verification problem includes receiving input comprising a design and properties that may be verified on the design. Verification processes are performed for each property on the design. A property verifiability metric value is established for each property in accordance with the verification processes, where a property verifiability metric value represents a difficulty level of verifying the property on the design. A design verifiability metric value is determined from the property verifiability metric values, where the design verifiability metric value represents a difficulty level of verifying the design.

Abstract: A test apparatus for testing a device under test includes a plurality of conversion processing units for converting split patterns recorded respectively on different split pattern recording sections in parallel, and a test pattern generating unit for providing a test pattern converted by the plurality of conversion processing units to the device under test, wherein a test pattern file used for testing the device under test includes a plurality of the split pattern recording sections where a plurality of the split patterns are recorded, and the test pattern for testing the device under test is split into the split patterns.

Abstract: A method for testing semiconductor chips having a test logic unit includes: providing a chip having n different register sets, each of which has m different registers that are subdivided into m register groups each having n registers, each register group respectively having only one individual register from a register set, the m register groups being uniquely identifiable using m headers; programming the m different register groups by filling them with m first bit strings, each bit string being respectively assignable to a state of n test modes; transmitting at least one header to select a register group and the state of the n test modes and executing the state of n test modes stored in the selected register group; and using a serial second bit string to read out test results or the status of the test modes.

Abstract: An apparatus that edits a test pattern used in a circuit function test includes a generator that generates a regular pattern that includes a plurality of unit patterns, by inserting a redundant pattern into a test pattern, and a pattern number reduction editor that defines the regular pattern as one unit pattern in the circuit function test.

Abstract: Read and write data steering logic in the I/O of a memory array is tested by providing a data bus lane for each addressable subunit of a memory array storage location. Each bus lane is connected to the data input of a comparator. A BIST controller writes test patterns to the memory through the write steering logic and reads the test patterns in parallel to test the write steering logic. The BIST controller writes test patterns to the memory in parallel and reads the test patterns through the read steering logic to test the read steering logic. In both cases, a separate comparator dedicated to each bus lane verifies that the subunit data was properly shifted between the data bus lane and memory storage location subunit. The comparators are effectively disabled during normal operations to prevent logic gate switching.

Abstract: Communications equipment can be tested using a test pattern encapsulated within a frame, and offsetting the test pattern in each successive frame. In equipment having a number of data latches receiving serial input, the introduction of the offset allows each latch, over time, to be exposed to the same pattern as the other latches. That is, the latches “see” different portions of the pattern at a given time, but over time, each can be exposed to the full pattern. Otherwise, each latch would “see” its own static pattern, different from the other latches, but the same over time with respect to itself. The offset can enhance diagnostic capabilities of the test pattern.

Abstract: A method, computer program product, and data processing system for combining results regarding test sequences' coverage of events in testing a plurality of related semiconductor designs are disclosed. Test patterns are randomly generated by one or more “frontend” computers. Results from applying these patterns to the designs under test are transmitted to a “backend” computer in the form of an ordered dictionary of events and bitmap and/or countmap data structures. The backend computer combines results from each test sequence in a cumulative fashion to measure the overall coverage of the set of test sequences over the plurality of designs.

Abstract: A method for testing at least one logic block of a processor includes, during execution of a user application by the processor, the processor generating a stop and test indicator. In response to the generation of the stop and test indicator, stopping the execution of the user application and, if necessary, saving a state of the at least one logic block of the processor. The method further includes applying a test stimulus for testing the at least one logic block of the processor. The test stimulus may be shifted into scan chains so as to perform scan testing of the processor during normal operation, such as during execution of a user application.

Abstract: A method of mitigating logic upsets includes providing an input to each of a plurality of programmable logic components, processing the input in each programmable logic component, determining an output from each programmable logic component, providing the output from each programmable logic component to a fixed logic component, examining the outputs, and determining a validated output from among the outputs. An architecture for mitigating logic upsets includes an input, a plurality of programmable logic components, and a fixed logic component. The input is provided to each of the programmable logic components. Each programmable logic components includes an encryption algorithm and a first majority voting logic, and processes the respective input to determine a respective output. The fixed logic component includes a second majority voting logic. The fixed logic component receives each respective output from the programmable logic components, examines the outputs, and determines a validated output.

Abstract: A serial point to point link that communicatively couples an integrated circuit (IC) device to another IC device is initialized by transferring a training sequence of symbols over the link. Registers of the IC device are programmed, to set a symbol data pattern and configure a lane transmitter for the link. A start bit in a register of the IC device is programmed, to request that the link be placed in a measurement mode. In this mode, the IC device instructs the other IC device to enter a loopback mode for the link. The IC device transmits a sequence of test symbols over the link and evaluates a loopback version of the sequence for errors. The sequence of test symbols have a data pattern, and are transmitted, as configured by the registers. Other embodiments are also described and claimed.

Abstract: A system and method to generate memory test patterns for the calibration of a delay locked loop (DLL) using pseudo random bit sequences (PRBS) generated through a pair of liner feedback shift registers (LFSR). The generated patterns are implemented on the system data bus as test patterns that closely simulate run-time switching conditions on the system bus, so as to allow more accurate calibration of the DLL. Test data write/read operations may be performed while signals for the test patterns are present on various bit lines in the data bus so as to allow for accurate determination or adjustment of the value for the delay to be provided by the DLL to the strobe signals during memory data reading operations at run time. Memory chips may also be tested over an operating range of values using the generated test patterns.

Abstract: A method for test data compression includes generating a plurality of test cubes, each test cube comprising test cube data. Each test cube is compared with at least one other test cube, as test cube pairs, to generate a compatibility rating for each compared test cube pair. The compared test cube pair with the highest compatibility rating is determined. The compared test cube pair with the highest compatibility rating is grouped into a test cube set. The remaining test cubes are grouped into test cube sets, as test cube pairs, based on the compatibility ratings of the compared test cube pairs. For at least one test cube set, a new codeword set is generated. Test cube data is grouped into blocks based on the new codeword set. Compression for the grouped test cube data is computed. A determination is made whether compression is improved as compared to a previous codeword set. If compression is not improved, the test cube set is encoded with the new codeword set to generate an encoded test cube set.

Abstract: There is provided a testing apparatus including: a pattern generator that generates an address signal and a data signal to be supplied to a plurality of memories under test and an expectation signal; a plurality of logic comparators that generate fail data when an output signal output from the plurality of memories under test and the expectation signal are not identical with each other; a plurality of fail memories that store the fail data generated from the plurality of logic comparators; a plurality of memory controllers that generate bad address information showing a bad address in the memory under test based on the fail data stored on the plurality of fail memories; a plurality of universal buffer memories that store the bad address information generated from the plurality of memory controllers; and a plurality of bad information writing sections that concurrently write bad information into the bad address in the plurality of memories under test, which is shown by the bad address information stored on the

Abstract: A hard disk drive system comprises N hard disk drive means for performing hard disk drive functions and is connected in a daisy chain, wherein N is greater than one. The system includes integrated system test (IST) means for testing and that is integrated with a first one of the N hard disk drive means and includes pattern generating means for generating test pattern data and pattern monitoring means for receiving a returned test pattern. The pattern generating means generates test pattern data that is routed from the first one of the N hard disk drive means serially through the remaining ones of the N hard disk drive means and back to the first one of the N hard disk drive means. The pattern monitoring means generates test result data based on returned test data returned to the first one of the N hard disk drive means.

Abstract: Training of a link is performed, wherein the link is an interconnect between two devices of a computer system. A built-in self-test (BIST) of the link is performed. A result from the link training is compared to a result from the BIST. A link status of the link is posted, wherein the link status is based at least in part on the result from the link training and the result from the BIST.

Abstract: The present invention is a test pattern generating method. And the test pattern generating method provides a counting step for counting the number of faults becoming undetectable respectively, at each of states 0 and 1 that are able to be given to each of input pins of EOR gates when each of the EOR gates becomes a D frontier (different frontier) or a J frontier (justify frontier), a selecting step for selecting a state in which the number of faults becoming undetectable is smaller in the 0 and 1 states as an allocating state to the input pin, based on a counted result at the counting step, and step for generating the test pattern based on a selected state at the selecting step. With this, dynamic compaction can be effectively executed by restraining the increase of the number of test patterns.

Abstract: The present invention enhances the Direct Access Stimulus (DAS) interface presently employed within a logic simulation hardware emulator to provide alternative stimulus to signals internal to a model actively running on a logic simulation hardware emulator. The present invention accomplishes this by introducing a set of special logic within the logic model to provide an alternate source for selected signals, identifies the special logic so that it is subsequently connected directly to the DAS card interface, and adds information to a symbol table so that this special logic can be identified as signal accessible through the DAS card interface. At runtime, when the user control program accesses facilities that have been connected to the DAS card interface, a set of special routines automatically reference the symbol table information to access the special logic that is connected to the DAS card interface.

Abstract: A test apparatus that tests a device under test is provided. The test apparatus includes: a pattern memory that stores in a compression format a test instruction sequence to define a test sequence for testing the device under test; an expanding section mat expands in a non-compression format the test instruction sequence read from the pattern memory; an instruction cache that caches the test instruction sequence which is expanded by the expanding section; a pattern generating section that sequentially reads instructions stored in the instruction cache and executes the same to generate a test pattern for the executed instruction; and a signal output section that generate a test signal based on the test pattern and provides the same to the device under test.

Abstract: The invention provides a number of related methods which improve the test and analysis of integrated circuit devices. A first method of the invention provides a method for pausing on a SCAN based test. A second method of the invention provides a method for using stimulations and responses of a known good device to increase fault coverage of patterns in a test flow. A third method of the invention provides a method to curve trace device buffers on an ATE.

Abstract: There is provided a test apparatus that tests a device under test. The test apparatus includes a pattern memory that stores a test instruction stream determining a test sequence for testing the device under test, an interval register that stores a repeated interval in response to the fact that the repeated interval showing at least one instruction to be repeatedly executed in the test instruction stream has been specified, an instruction cache that caches the test instruction stream read from the pattern memory, a memory control section that reads the test instruction stream from the pattern memory and writes the read stream into the instruction cache, a pattern generating section that sequentially reads and executes instructions included in the test instruction stream from the instruction cache and generates a test pattern corresponding to the executed instruction, and a signal output section that generates a test signal based on the test pattern and supplies the generated signal to the device under test.

Abstract: There is provided a test apparatus for testing a device under test.

Abstract: A test apparatus is provided. The test apparatus includes: a main memory that stores pattern data including at least one pattern bit defining a test signal provided to each of a plurality of terminals of the device under test; a pattern cache memory that caches the pattern data read from the main memory; a pattern generation control section that reads pattern data from the main memory and writes the same to the pattern cache memory; a pattern generating section that sequentially reads the pattern data stored in each cache entry of the pattern cache memory and outputs the same; and a channel circuit that generates a test signal corresponding to each of the plurality of terminals based on the pattern data outputted from the pattern generating section and provides the same to the device under test.

Abstract: The invention relates to a test method for determining a wire configuration for a circuit carrier having at least one component arranged thereon, where internal lines in the component are connected to component connections in a prescribed order, and where the component connections are wired to connections on the circuit carrier. According to the method, a respective prescribed test signal is applied to each internal line of the component using a controllable test signal generator integrated in the component. Output signals applied to the connections of the circuit carrier are tapped off. Thereafter, the respective output signals tapped off are identified with the corresponding test signals applied to the internal lines of the component using an external test apparatus for determining the wire configuration between the component connections and circuit carrier connections.

Abstract: In relation to the built-in self-test circuit (BIST circuit) for testing CAM macros, the present invention is intended to provide a means to enable reduction in amount of materials as required for wiring channel region for signal distribution, buffer, FF, etc., and in number of LSI pins, and further, to facilitate mounting on chips. The data generators for CAM testing, inserted between the APG for RAMs and CAM macros, create data to write to the CAM macros by obtaining the address signals directly or by decoding the same signals. The APG is common to all the memory macros, and testing proper to each CAM can be carried out by changing over the operation of the inserted data generators by means of the control signal. The data generators are arranged in the proximity of the CAM macros, the circuits to be tested.

Abstract: Disclosed is a test method for testing a data store having an integrated test data compression circuit where the data store has a memory cell array with a multiplicity of addressable memory cells, read/write amplifiers for reading and writing data to the memory cell via an internal data bus in the data store and a test data compression circuit which compresses test data sequences, which are each read serially from the memory cell array, with stored reference test data sequences in order to produce a respective indicator data item which indicates whether at least one data error has occurred in the test data sequence which has been read.

Abstract: A built-in-self test (BIST) scheme for analog circuitry functionality tests such as frequency response, gain, cut-off frequency, signal-to-noise ratio, and linearity measurement. The BIST scheme utilizes a built-in direct digital synthesizer (DDS) as the test pattern generator that can generate various test waveforms such as chirp, ramp, step frequency, two-tone frequencies, sweep frequencies, MSK, phase modulation, amplitude modulation, QAM and other hybrid modulations. The BIST scheme utilizes a multiplier followed by an accumulator as the output response analyzer (ORA). The multiplier extracts the spectrum information at the desired frequency without using Fast Fourier Transform (FFT) and the accumulator picks up the DC component by averaging the multiplier output.

Abstract: A method for reducing the number of transitions generated by an LFSR is introduced. The transition monitoring window monitors the number of transitions occurring as random patterns generated from an LFSR are applied to a scan chain, and, if the number of transitions exceeds a threshold value (“k-value”), all further transitions are suppressed. The transition monitoring window monitors the patterns entering the LFSR, incrementing a counter if a transition is detected. If a transition is detected just before the exit of a lowest stage of the LFSR the counter is decremented. The signal from the counter is compared with the k-value at every clock tick, and if the count is greater than the k-value, the vector most recently applied to the scan chain is re-applied to the scan chain; if it is less than the k-value, the output from the LFSR is applied to the scan chain.

Abstract: Programmable memory built-in self-test (MBIST) methods, apparatus, and systems are disclosed. Exemplary embodiments of the disclosed technology can be used, for example, to test one or more memories located on an integrated circuit during manufacturing testing.

Abstract: Bit error patterns for high speed data systems are generated by randomly distributing a first error pattern of G bits, output from a group of substantially uncorrelated bit error generators, into a second error pattern of N bits, where G and N are integers and G is less than or equal to N. In one embodiment, G bit error generators produce a G bit error pattern per bit period. Each bit error generator operates at a prescribed bit error rate. A distribution element randomly rearranges the order and placement of the G bits produced during a single bit period within an N bit grouping. The N bit group corresponds to N consecutive bits of data with which the error bits can be combined. Each bit error generator can be realized by a linear feedback shift register or its equivalent. Different primitive polynomials and different lengths can be used for each linear feedback shift register. In addition, outputs from fewer than all the shift register stages are utilized to generate each error bit.