[sdiy] State Variable Filter Practical Maximum Q

[James Patchell]

Scott Gravenhorst wrote:
> Hello all,
>
> Is there a practical maximum Q for an analog state variable filter?  I.e.,
> a maximum Q value at which the filter is stable and won't self-oscillate.
>
>
>
> -- ScottG
> ________________________________________________________________________
> -- Scott Gravenhorst
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>   
The maximum Q of a State Variable Filter is very dependent on  the 
quality of the active components in the circuit.  What you will notice 
is that as the resonant frequency is increased, the Q  will increase 
(refered to as Q enhancement).  The maximum Q will be dictated by the 
open loop gain of the amplifiers.  So the two most important parameters 
would be unity gain crossover and the open loop gain...(i.e..a 741 will 
just not work as good as a TL071 which will not work as good as a ..... ).

-Jim