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Mch lc tch cc 9 months, 3 weeks ago#113

cuonglm

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Mch lc tch cc: (Active filter)

C 4 loi mch chnh:- Mch lc thng thp.- Mch lc thng cao.- Mch lc thng di.- Mch lc ct di.

1. Mch lc thng thp (Low pass Filter-LPF)

- Mch lc thng thp cn bn:

Dng mch
http://diavatly.com/forum/6-in-t/113-mch-lc-tich-cc#113http://diavatly.com/forum/6-in-t/113-mch-lc-tich-cc#113http://diavatly.com/forum/6-in-t/113-mch-lc-tich-cc#113http://diavatly.com/forum/profile/userid-66http://diavatly.com/forum/profile/userid-66http://diavatly.com/forum/profile/userid-66http://diavatly.com/forum/profile/userid-66http://diavatly.com/forum/profile/userid-66http://diavatly.com/forum/6-in-t/113-mch-lc-tich-cc#113


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Nu ta chn R2=R1 th |Av0|=1

p tuyn tn s dc -20dB/dec v khi tn s tng ln 10 li 10 ln tc -20dB. Ngi ta hay dng mch voltage follower 1. y l mch khuch i khng o, nhng do khng c innn li bng +1.
http://diavatly.com/media/kunena/attachments/66/1_2012-01-15.JPG


3/20

Ngi ta thng chn Rf=R gim dng offset.

- Mch lc thng thp -40dB/dec:

Trong nhiu ng dng, ta cn phi gim nhanh li ca mcs ct, c ngha l dc ca bng tn phi ln hn na. lc bc cao.

Dng mch
http://diavatly.com/media/kunena/attachments/66/3_2012-01-15.JPGhttp://diavatly.com/media/kunena/attachments/66/2_2012-01-15.JPGhttp://diavatly.com/media/kunena/attachments/66/3_2012-01-15.JPGhttp://diavatly.com/media/kunena/attachments/66/2_2012-01-15.JPG


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Nu chn C2=2C1, ta c:

mch ny khuch i s gim i 40dB khi tn s tng lnln khi tn s tng ln 10 ln).


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- Mch lc thng thp -60dB/dec:

t c dc hn na-gn vi l tng-ngi ta dng ni tip vi mch lc -40dB/dec c dc -60dB/dec (tng ln 10 ln-gc pha ti tn s ct l -1350).

Dng mch cn bn nh hnh sau


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2. Mch lc thng cao (High-Pass Filter HPF)

y l mt mch m li ca mch rt nh tn s thp hcao hn th tn hiu qua ht. Nh vy tc dng ca mch lc thlc thng thp.

- Mch lc thng cao 20dB/dec:

Dng mch nh hnh di y l mch voltage follower nn AVbng vi in th 2 u in tr R nn:


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Khi tn s cao, tng tr ca t in khng ng k nn AV0=v0

n lc no li btu gim. Tn s m ti li gis ct. Lc ta c:

Ta cng c th dng mch nh hnh 2


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Dng mch


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Do l mch voltage follower nn in th 2 u R1 chnh l v0.


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Ngi ta dng 2 mch 40dB/dec v 20dB/dec ni tip nhau 60dB/dec.


12/20

Chn C1=C2=C3=C;


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.........

LMC

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Mch lc tch cc (tip theo) 9 months, 1 week ago#121

cuonglm

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Mch lc thng di: (band pass filter)

y l mt mch m ng ra ch c mt di tn gii hn ntn hiu a vo ng vo.
http://diavatly.com/forum/6-in-t/113-mch-lc-tich-cc/post?do=replyhttp://diavatly.com/forum/6-in-t/113-mch-lc-tich-cc/post?do=quotehttp://diavatly.com/forum/6-in-t/113-mch-lc-tich-cc/post?do=quotehttp://diavatly.com/forum/6-in-t/113-mch-lc-tich-cc/post?do=quotehttp://diavatly.com/forum/profile/userid-65http://diavatly.com/forum/profile/userid-65http://diavatly.com/forum/profile/userid-65http://diavatly.com/forum/profile/userid-72http://diavatly.com/forum/profile/userid-72http://diavatly.com/forum/profile/userid-72http://diavatly.com/forum/6-in-t/113-mch-lc-tich-cc#121http://diavatly.com/forum/6-in-t/113-mch-lc-tich-cc#121http://diavatly.com/forum/profile/userid-66http://diavatly.com/forum/profile/userid-66http://diavatly.com/forum/profile/userid-66http://diavatly.com/media/kunena/attachments/66/15_2012-01-15.JPGhttp://diavatly.com/forum/profile/userid-66http://diavatly.com/media/kunena/attachments/66/15_2012-01-15.JPGhttp://diavatly.com/forum/profile/userid-66http://diavatly.com/forum/6-in-t/113-mch-lc-tich-cc#121http://diavatly.com/forum/profile/userid-72http://diavatly.com/forum/profile/userid-65http://diavatly.com/forum/6-in-t/113-mch-lc-tich-cc/post?do=quotehttp://diavatly.com/forum/6-in-t/113-mch-lc-tich-cc/post?do=reply


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Vi mch ny in th ng ra v0maxt n tr s ti a mcng hng r.Khi tn s khc vi tn s cng hng, thp hn r lm li gim i cn 0.707v0max gi l tn s

rlm li gim cn 0.707v0maxgi l tn s ngt cao h.Bng thng c nh ngha: B=H - LKhi B0.1rc gi l mch lc di thng bng tn rng.

Attachment h2.JPG not found

Mch lc di thng bng tn hpDng mch
http://diavatly.com/media/kunena/attachments/66/hnh1.JPGhttp://diavatly.com/media/kunena/attachments/66/hnh1.JPG


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Ti tn s cng hng r:
http://diavatly.com/media/kunena/attachments/66/h3_2012-01-29.JPG


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T phng trnh (1) ta tm c:
http://diavatly.com/media/kunena/attachments/66/h4.JPG


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Mch lc di thng bng tn rng

Thng thng c mt mch di thng bng tn rng,lc h thng v thng thng mc ni tip nhau nhng phct2ca mch lc h thng phi ln hn tn s ct1ca m


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Phi chn R1, R2, C1, C2 sao cho 1< 2.

Mch lc loi tr: (di trit-Notch Filter)

y l mch dng lc b mt di tn s no trong tothng c dng lc b cc nhiu do mt b phnnonh tn s 50Hz, 60Hz hay 400Hz ca mt.C rt nhiu dng mch lc di trit, thng dng nht l mthng song song vi nhau hoc c th dng mch nh hnh


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