Around two or three months ago, we found one of the high voltage drivers was broken. Also, we found that the control of phase shifter always saturates. So we decided to buy a new high voltage driver with a larger dynamic range. However, we just realized yesterday that this large dynamic range high voltage driver has a worse phase behavior.

This work is done with IRMC locking, I just exchanged the high voltage driver. We could see from the attached figure. The old high voltage has a better phase margin.

So we are sacrificing phase margin to have a larger dynamic range. But we have a more stable phase behavior, so we should use back the old style high voltage driver to have a better locking performance.