【文章內(nèi)容簡介】
t be realized with lumpedparameter timeinvariant filters since an infinite number of poles is required. Delay lines have been employed to realize such a filter with fixed shaping times for short duration shaping in high energy physics . Delay lines are bulky, cause severe sensitivity of gain to temperature variations, have high cost when featuring a high delayrise time ratio, and may not easily vary in their time scale. On the contrary, variations in the time duration of the filter are required in order to optimise the signaltonoise ratio (SNR) or the resolution against throughput rate. Therefore, they are not considered ideal circuit elements for pulse processor energy channels. Recently, a quasi trapezoidal shape has been obtained by weighted addition of the outputs of a sin shaper [4]. The shape realization employs a cascade of active integrators with the highest frequency stage being the first one in the cascade. It follows that the flat top width depends on the number of stages in the cascade, the signal rise time is fixed, and long tail is present. The shape is an asymmetrical one. The Radeka timevariant filter (Gated Integrator: GI) approximates to a trapezoid by integrating (timevariant section) the output of a timeinvariant prefilter, usually the output of a semigaussian shaper, and Husimi and Ohkawa filter 4 approximates to a timevariant trapezoid by weighted sum of the outputs from internal stages of a