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:
Oct. 14, 2008
Filed:
Feb. 24, 2005
James T. Doyle, Nederland, CO (US);
Dae Woon Kang, Boulder, CO (US);
James T. Doyle, Nederland, CO (US);
Dae Woon Kang, Boulder, CO (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
On-chip AC noise suppression is provided for a target circuit within an integrated circuit chip. A power supply line filter is provided in the power supply line that feeds the target circuit. The filter includes a polysilicon resistor formed over a charged substrate well, with a dielectric material interposed between the well and the resistor. This decreases capacitive coupling between the substrate and the resistor, thereby suppressing AC noise that is injected via the substrate. For an on-chip bandgap reference circuit, AC noise suppression can be achieved by providing matched AC impedances in the PTAT and inverse PTAT branches of the circuit. This technique exploits the common-mode rejection capability of the error amplifier within the bandgap reference circuit. Also, the inputs of the error amplifier can be capacitively coupled together to exploit the amplifier's common-mode rejection capability for the suppression of AC noise that is injected at the amplifier inputs.