| 摘要 |
PURPOSE:To unnecessitate a phase shifter, to simplify a constitution, and to obtain this device at a low cost by controlling a phase shift amount by a phase lock loop(PLL) circuit which outputs a signal synchronizing with an input signal. CONSTITUTION:A phase comparator 1 which compares the phases of the two input signals, and outputs the result, is equipped with a logical circuit 2 which compares the phases, and switch elements FET 3 and 4 which are turned on and off according to the logical level of the output of the logical circuit 2. And also, a low-pass filter 5 which outputs a direct current signal according to the output signal of the phase comparator 1, is constituted of resistances 6 and 7, capacitor 8, operational amplifier 9, and reference power source 10. And also, a voltage control oscillator 11 changes an output frequency according to the output of the low-pass filter 5, and the output frequency is decreased according as an input voltage is increased. Then, the input signal is converted into the synchronizing and phase-shifted signal by the PLL circuit, and this phase shift amount is controlled by a control means. |
