Electric power conversion systems – Frequency conversion without intermediate conversion to d.c. – By semiconductor converter
Patent
1996-03-21
1997-09-02
Wong, Peter S.
Electric power conversion systems
Frequency conversion without intermediate conversion to d.c.
By semiconductor converter
363 8, H02M 522
Patent
active
056638787
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.
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Han Y. J.
Unitrode Corporation
Wong Peter S.
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