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:
Sep. 14, 1999
Filed:
Jan. 20, 1998
National Science Council, Taipei, TW;
Abstract
A second-order differential highpass filter constructed according to the present invention includes a difference amplifier and a feedback processing circuit. The difference amplifier includes an operational amplifier OP.sub.1, and four resistors R.sub.3, R.sub.4, R.sub.5 and R.sub.6, wherein R.sub.4 /R.sub.3 =R.sub.6 /R.sub.5. An input voltage V.sub.1 is fed to the inverting terminal (-) of the operational amplifier OP.sub.1 via the resistor R.sub.5. Another input voltage V.sub.2 is fed to the noninverting terminal (+) of the operational amplifier OP.sub.1 via the resistor R.sub.3. The output of the operational amplifier OP.sub.1 is fed back to the inverting terminal (-) of the operational amplifier OP.sub.1 via the resistor R.sub.6. The feedback processing circuit includes an operational amplifier OP.sub.2, two resistors R.sub.1 and R.sub.2, and two serial capacitors C.sub.2 and C.sub.1. The output of the operational amplifier OP.sub.2 is fed back to the inverting terminal (-) of the operational amplifier OP.sub.2 via the two serial capacitors C.sub.1 and C.sub.2, and is connected to the noninverting terminal of the operational amplifier OP.sub.1 via the resistor R.sub.4, and the noninverting (+) terminal of the operational amplifier OP.sub.2 is grounded. The inverting terminal of the operational amplifier OP.sub.2 is connected to the output terminal of the operational amplifier OP.sub.1 via the resistor R.sub.1. The two serial capacitors C.sub.1 and C.sub.2 are connected therebetween to one terminal of the resistor R.sub.2 of which another terminal is grounded.