The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 14, 1999
Filed:
Jun. 04, 1998
Yasushi Takahashi, Urawa, JP;
Tsutomu Takahashi, Tachikawa, JP;
Koji Arai, Kodaira, JP;
Shinji Bessho, Plano, TX (US);
Shunichi Sukegawa, Plano, TX (US);
Masayuki Hira, Dallas, TX (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
Realizing a reduction of the layout surface area by rendering unnecessary the region used for well isolation. In this DRAM, a triple well construction is used, and all of the regions for the unit memory cell array MA, the word line driver bank WDB, the sense amplifier bank SAB, and the cross area CR are surrounded by a lower layer N-type deep (deep layer) well 12. A back bias VPP corresponding to the power supply voltage of the word line driver is applied to the N well 14, and a back bias VBB corresponding to the characteristics of the memory cell are applied to the P well 16. In the N well 14, in regard to the P-type MOS transistors of the sense amplifier that undergo the substrate bias effect due to the back bias VPP, the threshold voltage is set to a low value so as to cancel that bias effect. Also, in the P well 16, in regard to the N-type MOS transistors of the sense amplifiers that undergo the substrate bias effect due to the back bias VBB, the threshold voltage is designed to a low value so as to cancel that bias effect.