Low-noise rf capacitance bridge transducer
Paul S. Linsay, D. H. Shoemaker · Review of Scientific Instruments · 1982
We have designed a low-noise servo system to both damp the motion of a high Q pendulum as well as measure the ground noise that drives it. The servo is based on a high-frequency low-noise capacitance bridge which is used as a displacement transducer for sensing the position of the pendulum. The bridge itself is servoed to minimize the need to adjust its components because of slow mechanical thermal drifts. Used as a displacement transducer we have achieved a position sensitivity of 4×10−11 cm/√Hz.