Virage Logic Corporation

Alliance Semiconductor Corporation

Daydreams LLC

Bruce L Prickett, Jr

Niranjan Behera

Yervant Zorian

Ritu Shrivastava

Jonathan Guy

Zahid Ansari

A method and system for repairing a memory. A test and repair wrapper is operable to be integrated with input/output (I/O) circuitry of a memory instance to form a wrapper I/O (WIO) block that is operable to receive test and repair information from a built-in self-test and repair (BISTR) processor. Logic circuitry associated with the WIO block is operable generate a current error signal that is used locally by the BISTR processor for providing a repair enable control signal in order to repair a faulty memory portion using a redundant memory portion without having to access a post-processing environment for repair signature generation.

System and method for repairing a memory

A method and apparatus for testing a memory at speed. A test and repair wrapper integrated with a memory instance is operable to receive test information scanned in from a built-in self-test and repair (BISTR) processor. Logic circuitry associated with the test and repair wrapper is operable to generate address, data and command signals based on the scanned test information, wherein the signals are used for effectuating one or more tests with respect to the memory instance.

System and method for testing a memory

A pulse width modulation scheme allows the creation of a unipolar pulse width modulated output signal. Two switching circuits (), preferably different legs of an inverter circuit, can operate to not only modulate an input voltage but also to reverse the polarity of the PWM output signal. Both switching circuits can be configured to accomplish both features, thus the switching load is spread out across all four switches.

Method and apparatus for providing pulse width modulation

A method of repairing over-erased flash EPROM cells (10) includes erasing the cells (12) and repairing the cells by a self-converging repair with a control gate bias (14), on a column by column basis. The self-converging repair includes grounding the sources (104) of the cells in a column, applying a pulsed bias voltage to the control gates of the cells (110), and a pulsed positive voltage to the drains of the cells (106). By varying the bias voltage at the control gate, the resulting threshold voltage of the cells after repair can be modulated to be greater than or less than an inherent steady state convergence value. Once one column of cells is repaired, the process is repeated on a subsequent column.

Self-converging over-erase repair method for flash EPROM

A row driving circuit (10) having a reduced number of transistors provides range of row deselect voltages, and eliminates the need for an NMOS pull-down device. The row driving circuit (10) has a-level shifter (14) formed by a PMOS input pull transistor P1 that is drain coupled at node V 10 to an NMOS input transistor N1. N1 functions as passgate for a row select signal and inverted row select signal applied to its gate and source respectively. A PMOS row pull-up transistor P2 has its gate coupled to V 10, its source coupled to a variable positive supply voltage (12), and its drain coupled to the source of a PMOS row select transistor P3. The drain and gate of P3 are coupled to switching circuits S 11 and S 12 respectively. S 11 and S 12 provide gate and drain voltages to quickly deselect the row by pulling the row to a negative deselect voltage. A PMOS erase transistor is also source coupled to the row with its gate coupled to switching circuit S 13 and its drain coupled to switching circuit S14. S13 and S14 provide a negative erase voltage to both the gate and drain of P4. In addition, S13 and S 14 can bias P4 into linear mode, allowing P4 to operate a leaker transistor, pulling the row down to a deselect voltage.

Growing community of inventors

Fremont, CA, United States of America

Bruce L Prickett, Jr