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Article: Ring-tone generator uses high-Q filter.(Technology Information)
- Article from:
- EDN
- Article date:
- May 11, 2000
- Author:
CopyrightCOPYRIGHT 2000 Reed Business Information, Inc. (US). This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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MODERN TELEPHONE applications need to generate a high-voltage sine wave to use as a ring-tone signal. Several familiar design alternatives generally involve either an IC-controlled flyback-type scheme or a ringer-module-"brick" approach. Unfortunately, module approaches are expensive, and flyback circuits are generally complicated and have inherent harmonic-suppression issues. The design parameters of both these approaches are generally fixed and offer little flexibility for users.
A simple yet effective method for producing a high-quality sine wave is to place a high-Q bandpass filter in a positive-feedback loop with a hard-limited gain element. This scheme ...
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