Electronic digital logic circuitry – Interface – Current driving
Patent
1998-02-26
2000-09-19
Tokar, Michael
Electronic digital logic circuitry
Interface
Current driving
326 81, 326 57, H03K 190175
Patent
active
061217956
ABSTRACT:
An input/output (I/O) circuit for transmitting output signals on or receiving input signals from an I/O terminal of an integrated circuit device, such as a Programmable Logic Device (PLD). The I/O circuit includes pull-up and pull-down transistors for generating output signals on the I/O terminal in an output mode, and an isolation transistor for limiting the voltage level transmitted to the pull-up transistor from the I/O terminal in an input mode. The isolation transistor is formed with a thicker gate oxide and a longer channel length than that of the pull-up and pull-down transistors, thereby allowing the isolation transistor to withstand voltages greater than Vcc of the PLD without damage. The isolation transistor is controlled using a charge pump provided on the PLD for programming non-volatile memory cells (e.g., EPROM, EEPROM or flash EPROM cells). The isolation transistor is produced during the same process steps used to produce high voltage transistors associated with the non-volatile memory cells.
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Curd Derek R.
Nguyen Hy V.
Bever Patrick T.
Cartier Lois D.
Tokar Michael
Tran Anh
Xilinx , Inc.
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