Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

how to choice power transistor in design 1~30MHz PA

Status
Not open for further replies.

josephz

Newbie level 5
Joined
Jun 24, 2007
Messages
9
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,335
mrf426

HI,
I am designing a 1~30MHz PA .The PA requires the output 130W and IMD3<-34dBc .The DC supply is +24V.
I chose the MHW592 ,MRF426 and MRF 422.But the IMD3 cannot satisfy the request.
The tansistor is right?
thanks!
 

Is there any eff spec requirement? Why not choose 50V device?
 

MRF422 is a 150W/28V transistor. From Motorola datasheet looks that it has approximately -36dBc at 130W but supplied at +28V.
I don’t think there will be more than 6dB degradation if you supply at +24V, but have to retune the output match for best IM3. Also try to increase a little bit the Icq quiescent current.
 

Yes,In the datasheet,when a MRF426 operats AB class, output 15W ,IMD3<-35dBc.
But I just can get IMD3=-17dBC.why?
 

That means, you didn't reach the rated P1dB.
 

There are a few things to improve the linearity of a power amplifier including tuning of the: input/output matching network, bias decoupling, harmonics termination, etc.

Also beware when you measure intermods with the Spectrum Analyzer. The fundamental power shall not overload the SA input, because this will produce intermods internally, which will deteriorate your results.
 

perhaps,the test is done when transistor doesnot operate wideband in the datasheet.Do you think so?
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top