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surianova
Joined: 01 Sep 2004
Posts: 399
Helped: 20
Location: ASIA
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 10 Dec 2004 3:06 bandwitdh for buffer |
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hi all,
Just want to confirm the way we measure the bandwidth for a buffer.
For buffer, the gain is normally almost 0 dB. Is it correct we measure
the bandwidth as 0-3dB= -3 dB. The frequency at gain -3dB is the
bandwidth, is it corerct?
Suria
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IanP
Joined: 05 Oct 2004
Posts: 6346
Helped: 1505
Location: West Coast
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| 10 Dec 2004 3:28 Re: bandwitdh for buffer |
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Yes, It is used not only for buffers, but amplifiers too.
This magic -3dB....and bandwidth..
For amplifiers there is another parameter which is called full power frequency, and this one describes the bandwidth at the maximum output voltage and without amplitude distortions...
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gevy
Joined: 17 Nov 2004
Posts: 377
Helped: 41
Location: Russia
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| 10 Dec 2004 6:33 Re: bandwitdh for buffer |
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-3dB frequency is frequency of half power.
For voltage or current
dB=20*lg(K) -> K=10^(dB/20) -> Power ~ K²=(10^(-3/20))²≈0.5
For power
dBp=10*lg(Kp) -> Kp=10^(dBp/10) -> Power ~ Kp=10^(-3/10)≈0.5
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flatulent
Joined: 19 Jul 2002
Posts: 4856
Helped: 292
Location: Middle Earth
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| 10 Dec 2004 6:44 Re: bandwitdh for buffer |
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| One thing to keep in mind is that buffers are intended for large amplitude signals into low impedance loads. You should measure and expect the bandwidth to be with a high level sine wave and lowest specified impedance load.
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segabird
Joined: 11 Nov 2004
Posts: 39
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| 13 Dec 2004 16:10 Re: bandwitdh for buffer |
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| flatulent wrote: |
| One thing to keep in mind is that buffers are intended for large amplitude signals into low impedance loads. You should measure and expect the bandwidth to be with a high level sine wave and lowest specified impedance load. |
which is the relation between sine wave frequency and the bandwidth?
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