| 摘要 |
PURPOSE:To cut off completely an output with a simple constitution, by using a means that controls the bias voltage which is applied to a diode of a multiplier and therefore varying the working state of the multiplier. CONSTITUTION:The output of a VCO1 forming a part of a PLL circuit is applied to a harmonic mixer 2 and compared with the reference frequency input of a reference frequency input terminal 3. Then an error output produced from the mixer 2 is fed back to the VCO1 via a loop filter 4. At the same time, the output of the VCO1 is applied to a multiplier 6 via a circulator 5. While the output of the filter 4 is applied to a synchronism detecting circuit 8, and the synchronizing state of the PLL is detected by the output of the filter 4 to be applied to a bias voltage generating circuit 11. The working state of the multiplier 6 is varied by the output of the circuit 11. Then a microwave output is completely cut off with a simple constitution. |
