Answers are grounded in this paper and cite their sources.
A fully integrated DTMF receiver has been fabricated on a single CMOS chip requiring only three external passive components. The circuit combines precision filters, zero crossing detectors and amplitude detectors with digital logic. Switched capacitor techniques are used to implement high-pass, bandpass, and bandstop filters. The receiver architecture and circuit implementation are described.
No takes yet. Share an insight, caveat, or question.
White et al. (1979) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: