Low-sensitivity easily trimmed standard building block for active rc filters

Four building blocks have been found that realise the biquadratic transfer function T(s)=K s2 + 2¿os + ¿oo2/s2 + 2¿ps + ¿op2 with very low sensitivities to variations in the passive and active components, and with the possibility of trimming ¿o, ¿oo, ¿op and ¿op independently each by one resistor. The networks may be manufactured in standardised integrated blocks which may be trimmed for specific applications.