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How to reduce second and 3'rd harmonic on low pass filter ?

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jackie1116

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Does anyone have this experience with is .and i want to know,as below

(1) Increase orders in passive Low pass filter whether it can reduce the harmonic

(2) i use NPO cap. and hight Q inductor whether it can reduce the harmonic

(3)if i design LPF and HPF on one board,what is importance to reduce harmonic


Hope advancer can help me !

very thank a lot!
 

Kral

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Re: How to reduce second and 3'rd harmonic on low pass filte

jackie1116,
The higher the order of a filter, the steeper the gain/frequency slope will be. So for a given cutoff frequency, a higher order filter will give more attenuation of harmonics. The ultimate slope of a low pass filter is 6n dB/octave or 20ndB/decade.
~
Higher Q inductors and capacitors will allow you to get closer to the ideal frequency response. Finite Q introduces additional resistive components that effect the frequency responce. The priniipal advantage of an NP0 caacitor is its small temperature coefficient of capcitance, although it does ave higher Q that other ceramic types.
Regards,
Kral
 

    jackie1116

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