An oversampling-based DTMF generator

Author

O´Leary, Paul ; Pauritsch, Manfred ; Maloberti, Franco ; Raschetti, Giampiero

Author_Institution

Joanneum Res., Graz, Austria

Volume

39

Issue

8

fYear

1991

fDate

8/1/1991 12:00:00 AM

Firstpage

1189

Lastpage

1191

Abstract

A circuit is described which uses one oversampling frequency synthesizer in an interleaved mode to generate dual-tone multifrequency (DTMF) telephone dialing tones. The synthesizer is based on direct digital synthesis using phase accumulation. The digital-to-analog conversion is carried out using a first-order sigma-delta converter. This sigma-delta converter requires only a simple second-order RC filter, eliminating the need for a switched capacitor filter. Measurements on the circuit confirm that all specifications of the DTMF are fulfilled

Keywords

digital-analogue conversion; frequency synthesizers; telephone station equipment; DTMF generator; DTMF tones; digital-to-analog conversion; direct digital synthesis; dual-tone multifrequency; first-order sigma-delta converter; interleaved mode; oversampling frequency synthesizer; phase accumulation; second-order RC filter; telephone dialing tones; Capacitors; Circuits; Clocks; Delta-sigma modulation; Digital filters; Frequency synthesizers; Read only memory; Signal generators; Smoothing methods; Telephony;

fLanguage

English

Journal_Title

Communications, IEEE Transactions on

Publisher

ieee

ISSN

0090-6778

Type

jour

DOI

10.1109/26.134006

Filename

134006