| 摘要 |
PURPOSE:To provide a variable delay circuit capable of optionally selecting the delay time in the initial state, simplifying the structure of a control circuit applying the delay time control signal, and capable of realizing the receiving/ phasing circuit of a ultrasonic diagnostic device allowing dynamic focusing with a simple structure. CONSTITUTION:Variable delay elements 30 each provided with variable capacitor diodes VC11, VC12 and a resistor R and changed with the capacity by the backward voltage applied to the variable capacity diodes VC11, VC12 to obtain the variable delay time are connected in tandem into multiple stages, delay signals of the stages 30-1 through 30-4 are outputted in parallel, and one of the outputs selected by a switching unit 31 is used as the circuit output signal. This variable delay circuit is used for the delay circuit of the receiving/phasing circuit of a ultrasonic diagnostic device. |
