Stmicroelectronics S.r.l.

Promod Kumar

Francesco Tomaiuolo

Luca Giuseppe De Ambroggi

Salvatore Nicosia

Fabrizio Campanale

Carmelo Condemi

Luigi Pascucci

Francesco Pipitone

Pierpaolo Nicosia

An Electric Wafer Sort (EWS) flow is implemented by expanding the functions of the micro-controller embedded in a FLASH EPROM memory device and of the integrated test structures. Test routines are executed by the onboard micro-controllers (that may be reading either from an embedded ROM or from a GLOBAL CACHE provided) internally without involving any external complex or expensive test equipment to control the test program. The device architecture is transparent from a tester point of view, with a standard interface having a set of defined commands and instructions to be interpreted by the on board microcontroller and internally executed.

Built-in testing methodology in flash memory

A method of synchronizing the start of sequential read cycles when reading data in a memory in a synchronous mode with sequential access uses the increment pulses as synchronization signals for the address counters of the memory cell array. Following each increment pulse, a dummy ATD pulse is generated. The dummy ATD pulse is undistinguishable from an ATD pulse generated upon detection of a switching of external address lines.

ATD generation in a synchronous memory

A delay circuit includes a first inverter connected to a supply voltage, and has an input for receiving an input signal. A delay regulating transistor is connected between the first inverter and a first voltage reference, and has a control terminal for receiving a biasing voltage. A capacitor is connected between an output of the first inverter and the first voltage reference. A second inverter is connected to the output of the first inverter for outputting a delayed output signal. An auxiliary current path is in parallel to the delay regulating transistor for allowing a portion of a discharge current from the capacitor to flow therethrough. The portion of the discharge current is proportional to the supply voltage. The auxiliary current path includes a diode connected to the first inverter, and a second transistor connected between the diode and the first voltage reference. The second transistor has a control terminal for receiving the biasing voltage.

Stabilized delay circuit

A multipurpose memory device suitable for a broader range of applications, whether requiring the reading of data in an asynchronous mode with random access (as in a standard memory) or in a synchronous sequential mode with sequential or burst type access, is capable of recognizing the mode of access and the mode of reading that is currently required by the microprocessor. The memory device self-conditions its internal circuitry as a function of such a recognition in order to read data in the requested mode without requiring the use of additional external control signals and/or implying a penalization in terms of access time and reading time compared to those which, for the same fabrication technology and state of the art design, may be attained with memory devices specifically designed for either one or the other mode of operation.

Interleaved memory device for burst type access in synchronous read mode with the two semi-arrays independently readable in random access asynchronous mode

A control circuit manages transferring of data within a system, such as an interleaved memory. The system includes a plurality of data sources for providing an output data stream synchronous with an external timing signal, an output register for storing data available at an output of the system, and a selection multiplexer for transferring the data from the plurality of data sources to the output register. The control circuit includes a plurality of circuit blocks, with each circuit block being dedicated to one of the plurality of data sources. Each circuit block includes a detection circuit for detecting availability of the data at an output of a selected data source, and a conditioned update path connected to the detection circuit provides an update flag. A logic gate having a first input receives the update flag and a second input receives an output signal from the detection circuit for providing a selection signal for the selection multiplexer.

Circuit for managing the transfer of data streams from a plurality of sources within a system

A redundancy architecture for a memory includes an array of memory cells divided into at least a pair of semi-arrays that are singularly addressable. Each semi-array is organized into rows and columns. The redundancy architecture includes a number of packets each including redundancy columns. The packets are divided into two subsets of packets. Each packet is addressable independently from the other by respective address circuits. Each packet also provides redundancy columns exclusively for a respective semi-array.

Redundancy architecture for an interleaved memory

An interleaved memory having an interleaved data path includes an array of memory cells divided into a first bank of memory cells and a second bank of memory cells, first and second arrays of sense amplifiers respectively coupled to the first and second bank of memory cells, and first and second read registers respectively coupled to the first and second arrays of sense amplifiers. A control and timing circuit is connected to the first and second arrays of sense amplifiers and has inputs for receiving externally generated command signals, and outputs for providing path selection signals and a control signal. A third register is connected to the first and second read registers and has inputs for receiving read data therein as a function of the path selection signals. An array of pass-gates are connected to the third register and are controlled in common by the control signal for enabling a transfer of the read data stored in the third register to an array of output buffers.

Interleaved data path and output management architecture for an interleaved memory and load pulser circuit for outputting the read data

An interleaved memory includes an array of memory cells divided into a first bank of memory cells and a second bank of memory cells. The interleaved memory operates in a burst access mode. A first address counter is coupled to the first bank of memory cells, and an address register is coupled to the first address counter and to the second bank of memory cells. A timing circuit generates increment pulses to the first address counter so that a first random access asynchronous read cycle starts with the first bank of memory cells. A function of an address counter for the second bank of memory cells is being performed by coping contents of the first address counter to the address register.

Interleaved memory device for sequential access synchronous reading with simplified address counters

A nonvolatile memory device has a signature code generator generating an new signature code as a function of data read from the cell array and the previously calculated signature code. Data are read in sequence, using an internal clock generated by an internal clock oscillator. In test mode, the memory is scanned sequentially, beginning from any memory location, selected randomly, and the signature code is variable in dynamic way; at the end of memory scanning, the signature code is compared to an expected result. Thus, testing may be performed at Wafer Sort Test Level, reading the memory cells at the memory operative speed, so as to ensure an early, fast and thorough detection of faults.

Nonvolatile memory and high speed memory test method

An address binary counter for an interleaved having an array of memory cells being divided into a first bank of memory cells and a second bank of memory cells includes as many stages as the bits that may be stored in the memory cells of a row of one of the banks, and a carry calculation network. The interleaved memory operates in a burst access mode enabled by an enabling signal. The carry calculation network includes an ordered group of independent carry generators. Each independent carry generator includes a certain number of stages, with each stage having inputs receiving its own enabling bit and a number of consecutive bits of a row of the bank equal to the number of stages, orderly starting from the least significant bit. The enabling bit of the first carry generator of the ordered group is the enabling signal, and the enabling bit of any other carry generator of the ordered group is the logic AND of the enabling signal and of the input bits of the preceding carry generator of the ordered group.

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Motta S. Anastasia, Italy

Promod Kumar