| 摘要 |
PURPOSE:To obtain a nonlinear analog signal, by applying a pulse signal in which the duty ratio is changed according to an input digital signal to a smoothing circuit via a parallel circuit of a resistor and a diode. CONSTITUTION:A digital signal for sound volume adjustment is applied to a pulse generating circuit 1 and converted to a pulse signal having the duty ratio on the digital value to switch a transistor (TR)2. The output of the TR2 is applied to a smoothing circuit 7 via a parallel circuit consisting of a diode 6 and a resistor 4. The output analog signal of the smoothing circuit 7 has a nonlinear characteristic to the input digital signal since the charge/discharge time constant of a time constant circuit consisting of a capacitor 5, diode 6 and resistor 4 has different charge/discharge time constant. Characteristics of types B and C can be obtained by applying the analog signal of this output to a variable gain amplifier 12 for gain control. |
