| 摘要 |
PURPOSE:To enable simple circuit constitution to provide fade-in and fade-out without using any digital multiplier, by varying the width of gate pulses supplied to an analog switch. CONSTITUTION:A PCM signal is converted by D/A converter 20 into an analog signal, which is switched by analog switch 40 with gate pulses whose period is equal to a sampling period and the output of switch 40 is smoothed by LPF30 to output an analog signal. This switch 40 is supplied with pulses from gate pulse generating circuit 50 that receives clock CK of frequency nfs (n) times sampling frequency fs and equalize the period of output CX to sampling period Ts. Then, fade-in and fade-out are provided without using any digital multiplier by making it possible to vary the pulse width of gate pulses according to the period of clock CK. |
