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  1. #1
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    corner frequency

    Hi folks,

    There is active RC filter with frequency tuning circuit. The tuning circuit results indicate that the RC time constant tends to be large. But the bandwidth of the filter tends to be wide. Is there any factor introducing the discrepancy? Thanks!

    •   Alt25th August 2009, 05:54

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  2. #2
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    tuning

    I like to answer you - however, I don´t understand your question, sorry.



    •   Alt25th August 2009, 08:39

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  3. #3
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    rc frequency chart for germany

    Thanks for your intention! The situation is that RC variation can vary the corner frequency of active RC filter. For keeping track of the RC variation, tuning circuit is used.



    •   Alt25th August 2009, 08:48

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    rc filter

    Quote Originally Posted by linuxwinner
    Thanks for your intention! The situation is that RC variation can vary the corner frequency of active RC filter. For keeping track of the RC variation, tuning circuit is used.
    Yes, but what is your problem now ?



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    rc circuit corner frequency

    The problem is that:

    Tuning circuit detects that master RC time constant is large. Large RC time constant means that the slave RC in active RC filter should be also large such that bandwidth of the filter should be narrow. But actually, the bandwidth of the filter is wider than expected. How come there is discrepancy?



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    calculate rc corner frequency

    It would help a lot if you would show us a drawing from the circuit.



    •   Alt25th August 2009, 11:33

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    active rc filter

    Quote Originally Posted by tzg6sa
    It would help a lot if you would show us a drawing from the circuit.
    Yes, I agree. How could we know without any drawing?



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    rc filter circuit

    As I understand is that the reference circuit indicating that 1/RC is lower than your reference clock frequency. But the change on the filter circuit is that the bandwidth is set to higher frequencies.

    This is correct!

    If you verify both, the reference tuner and the filter and apply the same process/temperature depend RC, the filter sould be with the tolerance or resolution of the setting method.



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