transistor frequency problem

[rky]

hi..........
i want to know that how to find minimum and maximum frequency of any transistor form data sheet.........
because i saw many data sheet but unable to know about the frequency range....
i am searching about high frequency power transistor like BU508.....
please help me.....
thank you
rky

 

[betwixt]

Generally, there is no low frequency limit.

The high frequency limit depends on how you use the transistor. Assume the gain will never be more than unity at 'ft' on the data sheet.

I would class the BU508 as a low frequency transistor, it's ft is only 7MHz, you can get them into tens of GHz.

Brian.

 

[rky]

thanks............
so there is a relation between gain and frequency as you said.....
so can we put gain lesser than 1 but frequency higher???
thank you

 

[betwixt]

Yes you can but what would it achieve. A gain of less than 1 is attenuation and it could be better done with a resistor.

Brian.

 

[rky]

actually i m looking for voltage amplification.....not current....
so will it be sufficient??

 

[FvM]

so will it be sufficient?

You didn't ask a specific question.

 

[rky]

it means that is there voltage amplification if my gain gone lesser than unity.....???
because above said that there is current amplification......
bt actually i dnt want to amplify current....i am looking for voltage amplification...