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:
Nov. 30, 1999
Filed:
Oct. 22, 1997
Barry Thornton, Austin, TX (US);
INT Labs, Inc., Austin, TX (US);
Abstract
A narrow band-pass interferometric filter for applying a response characteristic to an input signal to produce a filtered output signal. The filter is comprised of an inverting amplifier having an amplifying input to which the input signal is applied, an inverting input and an output. Coupled between the output and the inverting input of the inverting amplifier is an interferometric processing circuit which produces a signal having a generally constant positive amplitude except for a null at a pass frequency of the response characteristic for the filter. As the inversion of the signal produced by the signal processing circuit is the response characteristic of the filter and the amplitude thereof is greater than the amplitude of the input signal, the inverting amplifier passes the input signal whenever the frequency of the input signal matches the pass frequency of the filter. If, however, the frequency of the input signal is other than the pass frequency of the filter, the amplitude of the signal applied to the inverting input is greater than the amplitude of the input signal. Accordingly, the output of the inverting amplifier is driven to an inversion of the signal applied to the inverting input, The signal processing circuit may include a phase shift circuit which shifts the input signal by 180 degrees or a time delay circuit which delays the input signal by a time period generally equal to the period required for the input therealong.