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. 06, 2011
Filed:
Oct. 22, 2010
Tomoyuki Aihara, Osaka, JP;
Masanori Shirahama, Shiga, JP;
Yoshinobu Yamagami, Osaka, JP;
Marefusa Kurumada, Kyoto, JP;
Toshikazu Suzuki, Kanagawa, JP;
Tomoyuki Aihara, Osaka, JP;
Masanori Shirahama, Shiga, JP;
Yoshinobu Yamagami, Osaka, JP;
Marefusa Kurumada, Kyoto, JP;
Toshikazu Suzuki, Kanagawa, JP;
Panasonic Corporation, Osaka, JP;
Abstract
A semiconductor memory device includes a memory cell provided at an intersection of a word line and a bit line, a precharge circuit connected to the bit line, a column select circuit controlled in accordance with a write control signal, and a clamp circuit provided as a write circuit. The clamp circuit includes a transistor configured to control the potential of a selected bit line to a first potential (e.g., 0 V), and a variable capacitor configured to control the potential of the selected bit line to a second potential (e.g., a negative potential) which is lower than the first potential. The capacitance of the variable capacitor decreases when a power supply voltage is increased, whereby the amount of a decrease from the first potential to the second potential is reduced.