PHASE LOCKED LOOP(PLL) CAPACITY TESTER

PURPOSE:To obtain the PLL capacity tester capable of accurately measuring a pulling-in range and a holding range without taking labor. CONSTITUTION:A test signal generating means 30 generating a test signal for measuring the pulling-in range and holding range of a PLL control circuit 1 to be measured while changing frequency to input the same to the circuit 1 and a lock state judging means 6 inputting the test signal generated from the test signal generating means 30 and the feedback signal of the PLL control circuit 1 to judge the lock states of two signals are provided. Further, a frequency detection means 5 detecting the frequency of the test signal when the lock state judging means 6 judges the lock state of the signals when the frequency of the test signal is changed to change an unlock state to the lock state and the lock state to the unlock state is provided.