Altera Corporation

Altera Corporaiton

Bruce F Mielke

Matthew C Hendricks

Raminda U Madurawe

Myron Wai Wong

James D Sansbury

John C Costello

Ken A Ito

Lee R Althouse

Howard Marshall

Disclosed is a method and apparatus for evaluating margin voltages in single poly EEPROM cells. Briefly, the invention involves shifting the cell's threshold voltage higher, resulting in a corresponding rise in the margin voltage, so that testing for the erase margin may be conducted in the positive voltage range. The present invention implements a variety of solutions to the problem, including both innovations in cell processing and circuitry. In one embodiment, the process steps employed to create the floating gate transistor are changed in order to increase its threshold voltage. Alternatively, or in combination with these general process changes, the width of the floating gate transistor may be reduced, resulting in a corresponding increase in the margin voltage. Circuit modifications include providing a separate test mode condition where the sense amp trip current is higher than under normal operation, and raising the source line's voltage level with a new sense amp optimization, or only during the margin testing mode, both of which shift the erase margin voltages for the cell into the testable range.

Apparatus and method for margin testing single polysilicon EEPROM cells

An electronic circuit tester (e.g., for testing integrated circuit wafers or packaged integrated circuits) is provided. The tester is preferably based on a relatively inexpensive computer system such as a personal computer and includes at least one high-precision clock circuit that is programmable with respect to frequency and number of clock pulses. The high-precision clock circuit is connectable to the circuit being tested to permit certain timing-critical tests to be performed, even though a large number of other data channels in the tester are controlled by a relatively low speed clock circuit. The tester also includes analog circuitry that can be programmed to provide various analog signals suitable for performing parametric testing on an electronic device under test.

Electronic circuit testing methods and apparatus

A method and apparatus for maximizing the data transmission rate from a source data path to selected channels of a destination data path having a different width from the source data path. In a preferred embodiment, the data transfer circuit includes at least one transfer register that is typically of the same width as the data source. Each bit from the transfer register is input to a plurality of multiplexers, each of which typically selects a single bit and outputs the selected bit to the destination.

Data transfer circuit

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Los Altos Hills, CA, United States of America

Bruce F Mielke