Design Of Fast Timing Amplifier Of Ion Detector In CSRe Internal Target

Front-end electronics is an important part of the photon ion coincidence anticoincidence measurement. This thesis designs a high integration low noise and fast preamplifier timing detector according to the experimental requirements of the CSRe internal target.The output noise is low to 8.11 m Vrms, small-signal bandwidth is about 150 MHz, gain is 50×231V/A, leading edge timing precision is 24 ps.The current feedback amplifier is selected as the pre-amplifier because the current feedback amplifier is not limited by the gain bandwidth product. Capacitive-load isolation technique was proposed to improve the stability and capacitive load ability of the timing detector system in internal target of CSRe. This technique can solve the overshoot and ringing problems of the circuit,without affecting its gain and bandwidth. By constructing the circuit model,the cause of the instability of the circuit is analyzed mathematically, and the rationality of the capacitive-load isolation techniques is proved in experiment. It is demonstrated that the capacitive-load isolation technique can effectively eliminate the gain hump and the deteriorative frequency response caused by the capacitive load. Convolution method is used to analyze the front-end amplifier input capacitance influence on circuit, which not only affects the circuit gain but affects the bandwidth of the circuit and stability. The influence of the input resistance of the front-end of the amplifier on the circuit is analyzed in theory, which revels that great resistance will not only reduce the circuit gain error but also is not conducive to the improvement of signal-to-noise ratio. Aiming at the stability problem of operational amplifier in two stage cascade, two kinds of passive filters are presented in this thesis: first order passive filtering and second order passive filtering. Second order passive filtering can cause a certain overshoot and ringing phenomenon in circuit, while first order passive filtering can make the circuit more stable.