crhu
Junior Member
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I come, I see, and I go
Posts: 11
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Hi, forum, I am doing some device characterization, and I am really puzzled by the results I got for fmax and ft
fmax ~ the freq. @ which unity unilaterizated max power gain occurs
ft ~ the freq. @ which unity current gain occurs
Based on the equation: fmax = 1/2*sqrt(rds/Rg)*ft, for MOSFET, rds = 1/gds (~10k - 100k), Rg = Rpoly + Rchannel=1/3*W/L*Rsh + 1/5*1/gm (for long device) (~ 10 - 1k), fmax should be always larger than ft for MOSFET. However, the results I got always show that ft>fmax.
Thanks.
-ch
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