| 摘要 |
<p>The circuit is applicable to DTMF(Dual Tone Multi Frequency) signal generator, FSK(Frcquency Shiht Keying) Modulation, PSK(Phase Shiht Keying) modulation and other voice signal processing. A implementation comprises switches (A-M) to decide a potential of sine wave to vret, amplitade variation switches (I)(J) of the same tone, wave phase determining switches [(K)(L)(P), (M) (N)Q) , output voltege variation switches of switched capacitors (C1)(C2).... and condensers (C13)(C14) connected to operational amplifier (OPU). output signals from demodulator and logic circuit control the above switches to determine outputs proportional to capacitances of the switched capcitors.</p> |
