FT in transistor Опции

[Sara00]

hello my friends
i searched a lot in the internet and i couldn't find my answer.could you tell me what is exactly FT do in transistor?
what are the formula that join ft to another transistor elements for designing an oscillator or mixer?
if good book tell me more i will appreciate you.
Thanks

[Sara00]

Thanks all
i read the wikipeida before.but i asked many people about ft to choosing a transistor for desire job.for example if i want to create a collpits oscillator with 100Mhz frequency what transistor should i choose?what is the formula according the ft of transistor and my frequency?
could you help me ? its not very important to tell me in English.please tell me with your fresh language
its important to me to understand and know about electronics in RF environment