Preliminary Specifications for the PS Pick-ups Amplifier to be used in the Transverse Damping System

The pick-up amplification stage to be used for the CODD in the PS is presently under redesign. It appears that the constraints for the circuit are very similar to those of the transverse feedback project. The AB/BDI group and in particular its PI section has kindly agreed to fulfil the RF group constraints so as to obtain a common design with a common control interface. The reliability aspect is not treated here. Nevertheless radiation has been considered. At the locations foreseen for the pick-ups (SS 2, 94, 98), the annual dose measured on the vacuum chamber (ref: CERN-TIS-2002-06-TE) is about 1000 Gray per year. This value is to be compared to the 100 Gy considered as the critical dose for electronic circuits. The radiation problem has been solved for the CODD pick-ups using distance and shield (active circuits 2 meters below the floor composed of concrete slabs). The same lay out will be applied for the dampers with the drawback of the capacitive plates being loaded with a low impedance -5 meters long- cable.<br> With the cable properly terminated, the high pass behaviour was, until now, partially compensated using an integrating circuit, resulting in overall mediocre signal to noise ratio.<br> To overcome this weakness, the transmission cable would now be loaded with a resistance of high value for a low cut-off frequency and some properly designed components to absorb reflections in the upper spectrum.