Real-time loop gain and bandwidth measurement of phase-locked loop

We propose herein a simple and reliable technique to directly measure in real time the loop gain and bandwidth of a phase-locked loop (PLL). This technique can be used to make direct real-time measurements of the closed-loop gain of a PLL without breaking the locking state. We show the validity of the technique by demonstrating that the theoretical analysis is consistent to the experimental results with an actual PLL system. This simple technique with a systematic experimental configuration may easily be extended to the other PLL systems that require precise loop gain and bandwidth measurements.