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rf_man Junior Member Offline Posts: 28	ft=GBW? Aug 07^th, 2008, 12:40am Is it completely correct that the GBW of an amplifier is equal to the ft of the used technology?
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pancho_hideboo Senior Fellow Offline Posts: 1424 Real Homeless	Re: ft=GBW? Reply #1 - Aug 7^th, 2008, 12:55am rf_man wrote on Aug 7^th, 2008, 12:40am: Is it completely correct that the GBW of an amplifier is equal to the ft of the used technology? No, it's completely wrong. If you mean amplifier which is composed of single transistor and has no parasitic effect regarding bias, etc., GBW will be same as ft.
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buddypoor

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Re: ft=GBW?
Reply #2 - Aug 12^th, 2008, 12:38am

rf_man wrote on Aug 7^th, 2008, 12:40am:

Is it completely correct that the GBW of an amplifier is equal to the ft
of the used technology?

Normally, the term GBW is used only in case of integrated amplifiers (opamps). In this case, GBW is identical to the transit freqency only if the opamp is universal compensated (only one dominant pole in the amplifiying region).
If there is a second pole within this region, the GBW product is larger than Ft.

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pancho_hideboo

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Re: ft=GBW?
Reply #3 - Aug 13^th, 2008, 5:43pm

buddypoor wrote on Aug 12^th, 2008, 12:38am:

In this case, GBW is identical to the transit freqency only if the opamp is universal compensated (only one dominant pole in the amplifiying region).

Starter of this thread mentions "ft of the used technology" not transition frequency of amplifier like following.

rf_man wrote on Aug 7^th, 2008, 12:40am:

Is it completely correct that the GBW of an amplifier is equal to the ft of the used technology?

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buddypoor Community Fellow Offline Posts: 529 Bremen, Germany	Re: ft=GBW? Reply #4 - Aug 14^th, 2008, 1:11am Quote: Starter of this thread mentions "ft of the used technology" not transition frequency of amplifier like following. Hi, pancho_hideboo If ft is NOT identical to the transit frequency - what is it ? Please explain to me. Thank you.
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pancho_hideboo Senior Fellow Offline Posts: 1424 Real Homeless	Re: ft=GBW? Reply #5 - Aug 14^th, 2008, 1:19am buddypoor wrote on Aug 14^th, 2008, 1:11am: If ft is NOT identical to the transit frequency - what is it ? Please explain to me. When we refer to "ft of the used technology", it is a transition frequency of H21 of transistor at some bias condition(e.g. Vds=1.5V, Ids=1mA). This is NOT identical to the transition frequency of amplifier.
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buddypoor

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Re: ft=GBW?
Reply #6 - Aug 14^th, 2008, 4:13am

pancho_hideboo, thank you.
I was a bit confused as a phrase "ft of technology" is "uncommon" for my opinion..
However, if the transit frequency of the current gain for a transistor was ment, the original question sounds a bit "strange" to me, because it is logical that the GBW of an amplifier (containing some transistors, perhaps of different types) never can equal the transit frequency of one of the transistors.
Thanks and regards

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