What key instrument would you use to test a phaselocked loop
     What key instrument would you use to test a phase-locked loop oscillator?  Digital multimeter  Storage oscilloscope  Frequency counter  DIP switch with LEDs  A digital phase-locked loop in an IC controls the frequency of the  arithmetic-logic unit.  random-access memory unit.  reference oscillator.  voltage-controlled oscillator. 
  
  Solution
4
A phase-locked loop (PLL) is an electronic circuit with a voltage or voltage-driven oscillator that constantly adjusts to match the frequency of an input signal. PLLs are used to generate, stabilize, modulate, demodulate, filter or recover a signal from a \"noisy\" communications channel where data has been interrupted.
So the instrument used to test a phase locked loop oscillator is FREQUENCY COUNTER .
5 . A Digital phase locked loop in an IC controls the frequency of the Voltage controlled oscillator .

