Catalyst Semiconductor, Inc.

Adam Peter Cosmin

Sorin Stefan Georgescu

Radu H Iacob

Cornel D Stanescu

Adrian Macarie Tache

Horia Profeta

George Smarandoiu

Gelu Voicu

Carmen M Stangu

A non-volatile memory (NVM) system includes a plurality of NVM cells fabricated in a dual-well structure. Each NVM cell includes an access transistor and an NVM transistor, wherein the access transistor has a drain region that is continuous with a source region of the NVM transistor. The drain regions of each NVM transistor in a column of the array are commonly connected to a corresponding bit line. The control gates of each NVM transistor in a row of the array are commonly connected to a corresponding word line. The source regions of each of the access transistors in the array are commonly coupled. The NVM cells are programmed and erased without having to apply the high programming voltage Vacross the gate dielectric layers of the access transistors. As a result, the NVM cells can be scaled down to sub-0.35 micron geometries.

Scalable electrically eraseable and programmable memory (EEPROM) cell array

A non-volatile memory including one or more EEPROM cell pairs. Each EEPROM cell pair includes three transistors and stores two data bits, effectively providing a 1.5 transistor EEPROM cell. An EEPROM cell pair includes a first non-volatile memory transistor, a second non-volatile memory transistor and a source access transistor. The source access transistor includes: a first source region continuous with a source region of the first non-volatile memory transistor; a second source region continuous with a source region of the second non-volatile memory transistor, and a drain region that extends downward through a first well region to contact a second well region. The first, second and third semiconductor regions and the second well region have a first conductivity type, and the first well region has a second conductivity type, opposite the first conductivity type.

Scalable electrically eraseable and programmable memory

A digital potentiometer is disclosed that includes first, second, and third signal terminals. A chain of series-connected impedance elements with multiple tap points is connected between the first and second signal terminals. A plurality of first switching devices are each connected to a respective one of the multiple tap points and to an internal wiper node. A configurable output stage is connected between the internal wiper node and the third signal terminal. The configurable output stage includes a buffer and a second switching device. The second switching device is operable to bypass the buffer. A switching circuit controls switching of the first switching devices. The switching circuit includes a Gray-code counter, a Gray-code decoder, and a make-before-break circuit that controls the timing of the switching of the wiper switches.

Digital potentiometer including output buffer

Circuitry for programming a non-volatile memory of an integrated circuit is disclosed. The circuitry requires only three pins: a power pin, a ground pin, and a data pin. Programming mode is initiated by coincidentally applying high voltages at the power pin and the data pin. The memory cells may be programmed individually in sequence, or all at once. A clock signal for selecting the memory cells is obtained through serial high voltage pulses applied to the power pin. The clock signal increments a state machine, which in turn causes one or more of the memory cells to be selected. Binary data is provided to the data pin, is stored, and is then provided to the memory cells. A high voltage pulse subsequently received at the data pin is passed to the memory cells, and causes the stored data to be programmed into the selected memory cell(s).

System and method for programming non-volatile memory

A digital potentiometer, configurable and programmable using nonvolatile memory is disclosed. A unity-gain configured, rail-to-rail operational amplifier, used as voltage follower of buffer, can be inserted, by programming, between an internal wiper terminal and an output terminal of the digital potentiometer. This way, in certain applications, it is possible to take advantage of the low output resistance given by an analog buffer. The operational amplifier can be shutdown and bypassed by a switching device to provide a circuit behavior similar to a digital potentiometer without an output buffer. Using a dual-writing circuitry, first the complemented data, then the data itself, are written in the nonvolatile memory, improving the reliability. A Gray-code counter having a single bit changed at one time and no decode glitch is present. A make-before-break circuitry gives a short overlap conduction time for any adjacent pair of switches; one being turned-off while the other is turned-on. The resistor array is of high resistivity poly-type, with increased width and number of contacts, providing additional protection in short-circuited operation when the buffer is removed. The switches connected close to resistor array terminals are designed using ESD-proof rules.

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San Jose, CA, United States of America

Adam Peter Cosmin