Test of front-end circuit for suppressing common-mode component of main ring damper

To improve the efficiency of a transversal damper, the common-mode components in the beam signal due to any off-center closed orbit must be suppressed as much as possible. In the present Super Damper the common-mode suppression is accomplished by using a feedback to adjust the dc offset of the front-end integrator. For the proposed main ring damping system, a new front-end circuit using balanced cross-feed forward and feedback has been developed to improve the common-mode rejection and adaptability to changes in the closed-orbit of the front-end. The circuit had been proved on a bench test. The test done on July 30 was to evaluate its effectiveness on the real beam signals