| 摘要 |
<p>An ultrasonic generator is controlled by an integrated phase locked loop circuit. This PLL circuit includes a voltage-driven oscillator, a low-pass filter, and a digital phase comparator. The PLL circuit can clamp onto an input frequency close to a harmonic of the set free oscillating frequency of the oscillator. The absence of any frequency drift provides the necessary frequency stability for the narrow frequency band required for the ultrasonic welding of plastics.</p> |
