#### lhlbluesky

##### Banned

besides, i want to ask another question, for active filter (such as twin-t filter), how to decide and calculate the parameter of f0, Q, BW, gain? how to get the formula of them for a complicated transfer function (2-order or high order)? for 2-order filter, i know there is a typical formula just as :

vo/vi=A*w0/Q*s/(s^2+w0/Q*s+w0^2), but for a complicated transfer function or high order (4-order or 5-order) active filter, how to get the formula of f0 and Q? and what is the relationship of these parameters with opamp dc-gain?

if i want to make f0 accurate enough(tolerance 2%) , what methods should i use? and how to do trim for f0 control?

thanks all. pls help me.