ThermalRunaway
New Member
Hi Everyone,
Please see attached file for a simple Op-Amp Filter. As I understand it, the low frequency roll off is set by R1 & C1 and the high frequency roll off is set by R3 & C2. The formula used is F = 1 / 2pi rc.
With regard to R2, what effect does this have on the performance of the circuit? My initial thought was that the parallel combinatin of R2 and R3 would give you a new resistance to use in the formula F = 1 / 2pi rc and therefore a different high frequency roll off point but having set the circuit up it seems this is not the case. The addition of R2 did not change the high frequency roll off point, it merely changed the gain of the amplifier.
Can someone explain why this is?
Thanks, and apologies for the poor diagram.
Brian
Please see attached file for a simple Op-Amp Filter. As I understand it, the low frequency roll off is set by R1 & C1 and the high frequency roll off is set by R3 & C2. The formula used is F = 1 / 2pi rc.
With regard to R2, what effect does this have on the performance of the circuit? My initial thought was that the parallel combinatin of R2 and R3 would give you a new resistance to use in the formula F = 1 / 2pi rc and therefore a different high frequency roll off point but having set the circuit up it seems this is not the case. The addition of R2 did not change the high frequency roll off point, it merely changed the gain of the amplifier.
Can someone explain why this is?
Thanks, and apologies for the poor diagram.
Brian