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:
Jul. 26, 1994
Filed:
Jun. 15, 1993
Marshall L Hightower, Mountlake Terrace, WA (US);
James F Allen, Seattle, WA (US);
John Fluke Mfg. Co., Inc., Everett, WA (US);
Abstract
A high input impedance AC buffer for use in an instrument that does not require high frequency compensation or calibration. An op-amp receives an input signal that is to be measured via a high resistance input resistor and produces an output signal proportional to the input signal. A feedback resistor block and a feedback attenuator form the feedback path of the buffer and establish buffer gain. The low resistances of the feedback block and the feedback attenuator are substantially less than the resistance of the high resistance input resistor, precluding the need for compensation and calibration capacitors. A switching circuit operates to select resistors in the feedback resistance block and the feedback attenuator to provide predetermined gains for the buffer.