| 摘要 |
PURPOSE:To attain the changeover of delay time with excellent linearity by applying a control voltage to a varactor diode via a nonlinearity circuit having an opposite nonlinearity to a delay characteristic of the change in the varactor diode being a component of a delay line. CONSTITUTION:The delay line DL consists of an inductance element L of a single layer element L, plural varactor diodes Dv whose cathodes are connected to plural intermediate taps, and a bypass capacitor Cp connecting the anodes of the varactor diodes Vd to ground in common. A nonlinearity circuit 5 receiving an output voltage Vi of a D/A converter DAC has a function varying an output voltage Vi of the D/A converter DAC by the nonlinearity characteristic opposite to the delay change characteristic with respect to the control voltage of the varactor diode Dv to output a reverse voltage Vd (negative polarity) to the varactor diode Dv as the control voltage. Thus, the delay time is changed in a linear step in the delay line DL attended with the change in the digital control signal.
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