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:
Jan. 02, 1979
Filed:
Jun. 22, 1977
Don W Lake, Cupertino, CA (US);
Fairchild Camera and Instrument Corporation, Mountain View, CA (US);
Abstract
A solid state signal generator for producing frequency combinations such as used in multi-tone telephone systems. The output of a crystal oscillator is divided to obtain binary signals proportional to the selected pairs of the seven multi-tone frequencies. These signals are scaled with selected binary output signals generated by a free-running pattern generator and representing slopes at various points on a sine wave to produce a binary signal stream that is applied to a controlled charge digital-to-analog conversion circuit that partially charges or discharges a capacitor in accordance with the binary 1's and 0's to produce an output waveform across the capacitor that corresponds to the combined pair of selected individual tone frequency sinusoids.