It is more active than inactive. Just sayin'.It is not an active filter. It is simply a 1st-order RC passive filter feeding a buffer amplifier.
Typically if it's called an active filter, there is feedback from the output back to the filter elements, such as a Salen-Key. Just sayn'.It is more active than inactive. Just sayin'.
But it is.When i run AC analysis i do not find -3db point at 1.59Khz.
Its a passive RC filter with its output connected to an opamp gain stage.Hi Guys,
I was simulating the LPF using below circuit.
Calculated corner frequency = 1.59KHz
When i run AC analysis i do not find -3db point at 1.59Khz.
I also do not understand why initial magnitude is 6db.
Could anyone figure what i am missing here ?
Hi,But it is.
It's not where the absolute gain is -3dB, it's where the gain drops 3dB from the in-band gain (of 6dB).
If you look at the response at the plus input to the op amp, you will see the -3dB point from the in-band gain of 0dB.
Sure, with a slight modification.Is it possible to get the unity gain by using this circuit ?
Leave out R3Hi,
Is it possible to get the unity gain by using this circuit ?
Regards,
M
Yes, of course. However, if the filter transfer function must be the same, the components require a recalculation (modified design formulas for unity-gain feedback).Hi,
Is it possible to get the unity gain by using this circuit ?
Regards,
M
Not in this case - it is a first order filter with a buffer. All that is required is to change the gain of the buffer.Yes, of course. However, if the filter transfer function must be the same, the components require a recalculation (modified design formulas for unity-gain feedback).
Yes, of course. You are right. My answer applies to the Sallen-Key-structure.Not in this case - it is a first order filter with a buffer. All that is required is to change the gain of the buffer.
by Jake Hertz
by Jake Hertz
by Aaron Carman