Post subject: Why is high load resistance good?
Unread postPosted: Fri Jul 08, 2005 3:21 pm
is probably too basic so I feel a little foolish asking it here.
I'm not an RF engineer but I'm reading a thesis where they're talking
about GaN transistors and everyone is bragging about how it has
a large breakdown voltage and can take large load resistances. They
say the large load resistance helps in matching.
the large load resistance aid in matching?
I see it mentioned
all over the place but even introductory texts I've looked at mention
it as if "everyone already knows this".
Unread postPosted: Sat Jul 09, 2005
I believe this has to do with the fact some power
amplifiers require isolators at he output to improve IP3 and to
protect the the amplifer from reflections due to an antenna failure,
GaN is less susceptible to these issue compared
to GaAs and LDMOS.
But don't take my word for it, I have
no idea what I'm talking about.
Unread postPosted: Mon Jul 11, 2005 3:36 am
Joined: Tue Mar 15,
2005 11:43 pm
I'm trying my best to elaborate this issue. Yes, GaN and SiC
are well-known for their high impedance. Maybe you could look at
the point of view, due to they have wide bandgap, so it's possible
to operate under high-voltage operation with small current, that's
why the impedance is higher.
Secondly, regarding the "They
say the large load resistance helps in matching. " it refers to
Because when the impedance is high, means
the loss in input and output matching circuit will not be significantly
affect the overall circuit performance, as it won't turn the impedance
phase too much.
That is one significant property that enable
" single-stage wideband power amplifier design"
I hope it
Let me know if you need any help.
I'll try my best