The author presents a study of the influence of the order, n and m, of
a (CR)(m)-(RC)(n) shaper on the signal-to-noise, S/N, ratio of a read
-out system, subject to input referred f(2) noise emitted by the bipol
ar input transistor. As a Function of n and in, normalised equivalent
noise charges, ENC(n, m), are calculated. Conclusions and some guideli
nes for filter design are derived from the data obtained.