Lsi Logic Corporation

Lsi Corporation

Apple Inc.

Freescale Semiconductor,inc.

William D Schwarz

Ghasi R Agrawal

Mukesh K Puri

V Swamy Irrinki

Tuan L Phan

Jose A Tierno

Zheng Xu

Joseph Gergen

Jason T Nearing

Sunil Bhosekar

Sanjeev S Gokhale

An encoding/decoding scheme for pulse amplitude modulation (PAM) communications systems is disclosed. In one embodiment, a transmitter unit includes an encoder circuit and a transmit circuit. The encoder circuit is configured to encode an input data word having a first number of bits into a output data word having a second number of bits. The encoder performs a comparison operation to determine if at least one pair of subsets of the second plurality of bits includes bit values that are complements of each other. The encoder is further configured to modify the second plurality of bits if none of the pairs of subsets includes bit values that are complements of each other such that the modified second plurality of bits does include at least one pair of subsets that includes values complementary to one another.

Encoding and decoding for PAM transmitter and receiver

In one or more embodiments, a data processing system can include at least one core capable of executing instructions of an instruction set architecture and a triggered memory map access (tMMA) system coupled to the at least one core. The tMMA system can receive one or more events and, in response, perform one or more actions. For example, the actions can include transactions which can include a write to a an address of the memory map, a read from an address of the memory map, a read followed by write to two respective addresses of the memory map, and/or a fetch transaction. A result of a transaction (e.g., data read, data written, error, etc.) can be used in generating a trace message. For example, the tMMA system can generate a trace message that includes the result of the transaction and send the trace message to a trace message bus.

Event triggered memory mapped access

A test system includes a built-in self-test (BIST) circuit and a stress applicator for use in analyzing a memory array. The stress applicator applies a selective set of stress factors to the memory array, such as temperature and voltage conditions. The BIST circuit executes a test routine on the memory array to detect the presence of any faulty memory address locations that may arise under the prevailing stress condition. A full testing cycle involves iterative repetition of the functions performed by the stress applicator and BIST circuit, with variations in the stress factors across the testing iterations. An accumulator cumulatively stores the fault information generated by the BIST circuit during each testing iteration. Following completion of the testing cycle, a repair operation is performed by a built-in self-repair (BISR) circuit to remap the faulty memory address locations indicated by the accumulator to redundant memory address locations.

Method and system for performing built-in-self-test routines using an accumulator to store fault information

Method and system for performing built-in self-test routines using an accumulator to store fault information

A method for testing semiconductor devices advantageously increases manufacturing yields. The method includes generating memory repair data for a wafer die by writing at least one predetermined digital bit pattern into a memory on the wafer die, reading the at least one predetermined digital bit pattern back out of the memory, comparing the at least one predetermined digital bit pattern read out from the memory against the at least one predetermined digital bit pattern written into the memory, and storing results of the comparison as the memory repair data. The writing and reading are performed a plurality of times, each time with a different voltage and clock frequency combination being applied to the wafer die. The memory repair data is programmed into the wafer die, and the wafer die is assembled into a packaged semiconductor device. The packaged semiconductor device is tested by causing the memory repair data programmed within the packaged semiconductor device to be transferred into the memory a plurality of times, each time with a different voltage and clock frequency combination being applied to the packaged semiconductor device.

Method for testing semiconductor devices having built-in self repair (BISR) memory

A method is presented for built-in redundancy analysis of a semiconductor memory device. The method does not require retention of an entire memory bitmap, and may be implemented on-chip and integrated within existing BIST circuitry. The regular memory is comprehensively tested, and defective rows and columns are flagged for replacement by redundant rows and/or columns; the elements containing the most defects are the first to be flagged. If all of the defective memory locations can be replaced using redundant rows and columns, the method designates the memory as repairable; a repair solution may then be scanned out of the memory device. The method is believed to provide a fast, cost-effective means of testing and repairing memory devices, with a consequent improvement in production yields.

Built-in redundancy analysis for memories with row and column repair

A fast method and apparatus for built-in self-repair (BISR) of memory arrays is disclosed. In one embodiment, an integrated circuit includes a repair circuit coupled between the address decoder and the memory array. The address decoder receives memory addresses and asserts corresponding word lines. The memory array has default words associated with the word lines, but also includes extra words. By default, the repair circuit maps the word lines from the address decoder to the memory array word lines for the default words. However, the repair circuit includes at least one latch for each of the decoder word lines. When a latch is set, the repair circuit isolates the decoder word line from the default word and remaps the decoder word line to an extra word in the memory. The latches remain set while as long as power is applied, so that accesses to faulty memory words are automatically rerouted without any additional overhead relative to accesses to functional memory words. This may advantageously provide significantly reduced memory access times for only a small increase in hardware cost.

Fast built-in self-repair circuit

A memory device configured to detect changes in fault patterns is disclosed. In one embodiment, the memory device includes a memory array, a built-in self-test (BIST) unit, and a built-in self-repair (BISR) unit. The BIST unit runs test patterns on the memory array to identify faulty locations in the array. A comparator within the BIST or external to the BIST compares the actual output of the memory array to the expected output, and asserts an error signal whenever a mismatch occurs. The BISR unit intercepts addresses directed to the memory array, and operates on the addresses in three distinct phases. During a training phase, the BISR unit stores the intercepted addresses when the error signal is asserted. During the normal operation phase, the BISR unit compares all intercepted addresses to stored addresses and redirects a corresponding memory access if any intercepted address matches a stored address. During a verification phase, the BISR unit compares intercepted addresses designated by assertions of the error signal to the addresses previously stored in the training phase. If the faulty intercepted address fails to match a stored address, the BISR unit asserts a &ldquo;new error&rdquo; signal. If at the end of the verification phase, a stored address has not matched nay intercepted faulty address, the BISR asserts a &ldquo;missed error&rdquo; signal.

Multi-condition BISR test mode for memories with redundancy

A single-chip integrated circuit includes a memory array, a built-in self test circuit and a pause circuit. The built-in self test circuit is coupled to the memory array and is adapted to execute a sequence of write and read operations on the memory array. The pause circuit is coupled to and activated by the built-in self test circuit. When activated, the pause circuit pauses the sequence of write and read operations for a pause time period.

Built-in self repair circuit with pause for data retention coverage

An integrated circuit device is disclosed having a BIST Uinit with recolfiLgurable data retention testing for a memory array. In one embodiment, the integrated circuit device includes a memory array, a BIST unit, an externally-programmable pause count register, and a pause counter. The BIST unit is configured to apply a test pattern of memory accesses to the memory array. The test pattern preferably includes a first phase for writing data values to the memory array, a second phase for stressing the memory array, and a third phase for verifying the data values after the array has been stressed. The length of the second phase is determined by the count stored in the externally-programmable register. The count may be loaded into the pause counter by the BIST prior to the second phase. In the second phase, the BIST unit asserts a pause signal which causes the pause counter to suppress the clock signal to the BIST unit during the second phase, thereby suspending the BIST unit's activity. The pause signal may also initiate &ldquo;disturbances&rdquo; to the memory array during the second phase, such as degrading the power supply voltage and initiating the activity of a sub-BIST unit that conducts memory accesses near a target memory location designed to &ldquo;stress&rdquo; that target memory location. Once the pause counter finishes counting, the clock signal to the BIST unit is re-established, allowing the BIST unit to conduct the verification phase.

Built-in self-test unit having a reconfigurable data retention test

An efficient methodology for detecting and rejecting faulty integrated circuits with embedded memories utilizing stress factors during the manufacturing production testing process. In the disclosed embodiment of the invention, a stress factor is applied to an integrated circuit having built-in-self-test (BIST) circuitry and built-in-self-repair (BISR) circuitry. A BIST run is then performed on a predetermined portion of the integrated circuit to detect a set of faulty memory locations. The results of this first BIST run are stored. A second condition is applied to the die and a second BIST run is executed to generate a second set of faulty memory locations. The results of the second BIST run are stored and compared with the first result. If the results differ, the integrated circuit is rejected. Thus, a methodology for screening out field errors at the factory is disclosed using BIST/BISR circuitry.

Redundancy analysis for embedded memories with built-in self test and

A reconfigurable built-in self test circuit for enabling the debugging of an embedded device. In one embodiment, the write data path from the built-in self test module to the embedded device includes a multiplexer which is controlled by a debug signal. When the debug signal is de-asserted, the multiplexer forwards the write data from the built-in self test module to the embedded device, thereby allowing the self test to proceed in the hard wired manner. When the debug signal is asserted, the multiplexer forwards external data from the user to the embedded device, thereby allowing the user to execute customized tests on the embedded device. A second multiplexer is similarly placed in the expected data path from the built-in self test module to the comparator to allow the user to provide external data for comparison with output data from the embedded device when the debug signal is asserted. For all tests, the address and control data is provided by the built-in self test module to avoid the need to implement an external access to these data paths.

Reconfigurable built-in self test circuit

A method for testing a memory device which statistically characterizes the failure time for a subset of cells sampled from the memory array before performing testing of the memory array in general. The memory device includes a testing unit which determines the failure times for cells in the sample subset, and a parameter calculation unit which computes one or more statistical parameters from the failure times. These statistical parameters are then used to determine a refresh pause time which is used in a data retention test of the memory array. The testing method may be performed when power is applied to the memory device. Thus, the BIST method may provide for the accurate detection of memory faults in the memory array at any power-up temperature. In addition, the testing method may be performed after the memory array attains an operational temperature, or in response to an operating system command.

Refresh sampling built-in self test and repair circuit

A test circuit is provided for detection of data retention faults and cell stability faults of a memory array, such as a static random access memory (SRAM). The memory array test circuit comprises a weak write test circuit, a memory array address decoder, a microprocessor and display unit. During testing of the memory array, the weak test circuit controls the address decoder to decrease the voltage on the word lines so that it is less than the threshold voltage of the memory array transistors. The microprocessor then writes an inverted data to the memory array and then reads it. The read inverted data is sent to the display unit for comparison with a known template. By comparing the read inverted data to the template, defective memory cells can be identified.

Growing community of inventors

Austin, TX, United States of America

William D Schwarz