A structure consisting of a preamplifier with a field-effect transistor, a differential amplifier, a noise filter with a symmetric triangular pulsed characteristic and a gating integrator is considered. It is shown that in such system the minimum equivalent noise charge corresponds to zero gating pulse time, i.e. the gating integrator is equivalent to the peak detector. Comparison with the (RC-CR)-filter at the gating integrator input is carried out. 6 refs.; 3 figs.