Designing Wide bandwidth amplifier

[azlishah]

Hi there....

I'm new in this forum and I'm student MSc in Elec.Communication.I have a problem to do a project about designing a wideband amplifier freq above 2.4 GHz. It's kind if one of u can help to on how to design or can give me the schematic circuit or the relevant website for me to complete this task. Ur kind is much appriceate.

Thanx...

 

[fastelec]

Will you put some more info about this project?
How wideband should be your amplifier?
output power? and so on

 

[azlishah]

Hi ...

about this wideband amplifier:-

freq > 2.4 GHz using BJT or FET
will simulate using ADS
will be fabricate using PCB.

The problem is i can't find a suitable circuit for this one. Could u pls help me...

Thanx

 

[springf2000]

that is simple,visist the www.sirenza.com, then y can got more information

 

[VSWR]

azlishah,

I think you should respond properly to fastelec's questions if you expect us to help you. What is the lower and upper frequency limits, gain, output power?

Will you put some more info about this project?
How wideband should be your amplifier?
output power? and so on

 

[kent616]

For wide band amplifier...two type of maching network mostly ppl do.....1) compensated nework matching 2) negative feeback network....but I'm not sure which one suit ur porject.....

Added after 3 minutes:

go search for Microwave Transistor Amplifier --- Second Edition by Guillermo Gonzalez...it is a very good book...

 

[Element_115]

A very common and good method for wideband design is to use couplers.
Use a Lange or 90° coupler to put two amps in parallel. This helps VSWR
Pout (~ +3dBm), and extends bandwidth. See Pozar.


Hope this helps
Cheers

 

[footprint]

I think it's easy to design it with MMIC
..........................

 

[kent616]

used lange coupler to design balanced amplifier is the best recently....

Added after 3 minutes:

I hope that it will help...good luck

 

[eladg]

used lange coupler to design balanced amplifier is the best recently....

Added after 3 minutes:

I hope that it will help...good luck

lange cou[ler is not the best way to do it. (it is on pcd)

use branche line coupler

 

[azlishah]

Dear friends,

Sorry to disturb u...I just got the specification on this amplifier
- to build an amplifier (TWA) with a bandwidth in excess of 5GHz using filtronic InP pHEMTs
-The gain is 10dB +/- 0.1dB
-S11 and S12 below 15 dB
Input and Out put Impedance shoulbe be 50 ohm
Hopefully u all can help me on doing this project.

Regards
SHAH

 

[boy]

You might try a distributed amplifier (i think some author also call it TWA) . with only 10 dB gain. I thin it is doable. This is a book

 

[wjnbry]

i think you should try a feedback amplifier.but i have never designed.
you pick up the book--Broadband Microwave Amplifiers.
some good examples in it.

 

[runner4wd]

In order to design your amplifer with the spec you provided is hard because the S21 and S11 of the HMET or any semiconductor will vary with frequency all I can say at this stage (having done no quantitive analysis) it is very difficult to obtain 10dB gain form a S21 of 15dB which is not same throughout the band of interest.
Initially we may think that cascading different stages of low gain about 5dB may help but the problem will be the matching network and the elements used to match an inductor or capacitor will not behave as expected and you will find lot of resonant peaks.
The topic might be intresting for MS thesis but i dont think any practical communication circuit will use this kind of amplifier