Apparatus and method for generating a low frequency AC signal
US5663878A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 21, 1996 |
| Grant date | Sep 2, 1997 |
| Priority date | — |
| Expiry date | Mar 21, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02M7/4807
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An apparatus and method for generating a low frequency AC signal such as a ringing voltage signal for a telephone subscriber interface unit or the like. The apparatus comprises an oscillator which drives a pair of counters whose outputs differ by a desired low frequency. The output of the first counter is fed to a controlled current source so as to excite a resonant tank circuit and thereby provide a high voltage sinusoidal signal. The output of the second counter drives a switch which samples the high voltage sinusoidal signal. An alias frequency is thus generated which is filtered by an output capacitor. The method comprises steps which follow directly from the above-described apparatus.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.