| 摘要 |
PURPOSE:To prevent the overload operation of a power amplifier and the continuity of discharge for arrestor, etc., by performing the detection of reflection independently of the phase difference between a load current and a load voltage and the variance of current amplitude. CONSTITUTION:When the load impedance is in variance toward the output current of a power amplifier to be increased, a positive voltage is produced across a resistor 52, and when fluctuated toward the output current to be decreased, a positive voltage is produced across a resistor 53, and a logical output is obtained by the reference voltage and a voltage comparator 55 by selecting larger voltage through diodes 48 and 49. On the other hand, since high frequency transformers 36, 37 and diodes 381-384 act as a phase detector, a voltage in proportion to the output voltage and the phase difference of the output current is produced across resistors 391, 392, and if a positive voltage is produced at the resistor 391 at a leading phase, a positive voltage is produced at the resistor 392 at lag phase. Further, a greater voltage is selected and it is compared with the reference voltage at the voltage comparator 54 to obtain an output. |
