Title :
An oversampling-based DTMF generator
Author :
O´Leary, Paul ; Pauritsch, Manfred ; Maloberti, Franco ; Raschetti, Giampiero
Author_Institution :
Joanneum Res., Graz, Austria
fDate :
8/1/1991 12:00:00 AM
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;
Journal_Title :
Communications, IEEE Transactions on
