What is phemt and its biasing condition?

[ahmer saeed]

what is phemt?what is the biasing condition of phemt?Is its biasing condition is same as N channel FET?

 

[Beepster]

pseudomorphic high electron mobility transistors
for very high frequency work (~60ghz)

 

[zfl]

Re: what is phemt?

It's right! HEMT mainly works for very hign frequency(>100GHz) and is
relatively expenseiver than GaAS MESFET!

 

[mzewani]

Re: what is phemt?

yes but this does not mean that you can not use it for lower frequency
the new tech now is e phemt which mean enhanced phemt there is no need for the negative biase in the gate so you need only one source for your dc bias circuit

 

[stanleyu]

Re: what is phemt?

Yes I know Agilent is using Ephemt process;Win Semiconductor of Taiwan also using it. and numerous other such as RFMD and Triquint ....
Anyway, overall it has very good NF at lower frequency for LNA design and excellent linearity for power amplifier design and its ft can can be as high as 40GHz ....

 

[J1Lee]

Re: what is phemt?

Except for E PHEMT, you just bias the PHEMT the same way you would bias the N-Channel GaAsFET devices. You just need to follow the manufacturer's bias recommendations. From the application standpoint, PHEMT is just the new technology that offers better performance than GaAsFET, e.g. higher cutoff frequency Ft, better efficiency (lower Vds), better noise figure, higher gain, higher IMD3, etc.

 

[v4eda]

Re: what is phemt?

what is phemt?what is the biasing condition of phemt?Is its biasing condition is same as N channel FET?

pHEMT (pseudomorphic HEMT) is basically a FET with a different epitaxial active layer & doped such that the electron motion is less random.The transconductance of these devices are higher (hence have higher gain) as compared to the MESFET and also they have very low intrinsic noise figures. these devices also have gate dimensions of the order of 0.15 - 0.25 micron and hence the exhibit very high cut-oof frequencies of the order of 60 to 70 GHz; these devices are also used for Power amplifiers do to their higher current carrying capacity.
As far as the biasing condition is concerned, the biasing is similar to the
N channel FETs except for a Enhancement mode HEMT where only +ve supply is used for the gate and drain biasings. 8)