# About the transit frequency fT in Chapter 2 of Razavi's book

1. ## About the transit frequency fT in Chapter 2 of Razavi's book

It is about Razavi's book Design of Analog CMOS Integrated Circuits, in the problems of Chapter 2 there is a problem 2.13 about fT, but you know in Razavi's book Chaper 2 doesn't deal with anything about the concept of transit frequency so I am a little bit confused about this problem, I feel difficult to solve problem2.13, can someone give me some suggestions about solving the problems after each chapters.

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2. ## About the transit frequency fT in Chapter 2 of Razavi's book

there is a solution manual available on the board just search for it

https://www.edaboard.com/ftopic103362.html

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3. ## Re: About the transit frequency fT in Chapter 2 of Razavi's

Originally Posted by safwatonline
there is a solution manual available on the board just search for it

h**p://www.edaboard.com/ftopic103362.html
Thank you for your link, but I have already got the solution manual, can you tell me some more details about the issue of fT.

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4. ## About the transit frequency fT in Chapter 2 of Razavi's book

hello,
ft is the frequency at which the current gain equal unity, as in the solution manual u get the input current and output current and hence the current gain then equate it to unity to obtain the ft expression.
cutoff freq. is the frequency at which the MOS doesnt amplify the signal no more.

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5. ## Re: About the transit frequency fT in Chapter 2 of Razavi's

Originally Posted by safwatonline
hello,
ft is the frequency at which the current gain equal unity, as in the solution manual u get the input current and output current and hence the current gain then equate it to unity to obtain the ft expression.
cutoff freq. is the frequency at which the MOS doesnt amplify the signal no more.
Thank you, nice explanation!

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