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.

Impedance matching on Rf PCB

enemra

Junior Member level 1
Joined
Oct 19, 2011
Messages
19
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,440
I have two questions in the image that I have attached. the image is of a power amplifier board.
  1. The output of the amplifier has irregular copper trace with different length until the output SMA, which I pointed as (1). Doesn't this impact the impedance of the trace?
  2. What is the use of two vertical traces before the output SMA, which I pointed as (2)?
enter image description here
Thank you
 
1. Stepped quarter wave transmission line for impedance matching
2. Transmission line stop filter for (probably 2nd) harmonic suppression
 
Should be a matching network, from the moment that in the datasheet is mentioned that the output impedance of BLF2425 is about 2.5ohms at 2450MHz.
 
Thanks to all who answered. Amazing.... Learning on RF part is never ending :( Thanks for the heads up.
 
The section (1) is a matching network, his function is to present to the transistor some specific impedances (trade-off between efficiency and power output) in the band of interest.
The wide lines are near to the trans are low impedance, by stacking them together a transformer is created. Usualy this kind of network can be quarter wave sections / exponentiel tapper / or even Klopfeinstein taper (non linear step).

The section (2) is with no doubt a low-pass filter as an harmonic filter . The central freq of BLF2425 is 2.4GHz and according to the length of the stubs are tuned @ around 4.8GHz see attached a 10s quick EM simul.
 

Attachments

  • Sans titre.png
    Sans titre.png
    82.6 KB · Views: 105
The section (1) is a matching network, his function is to present to the transistor some specific impedances (trade-off between efficiency and power output) in the band of interest.
The wide lines are near to the trans are low impedance, by stacking them together a transformer is created. Usualy this kind of network can be quarter wave sections / exponentiel tapper / or even Klopfeinstein taper (non linear step).

The section (2) is with no doubt a low-pass filter as an harmonic filter . The central freq of BLF2425 is 2.4GHz and according to the length of the stubs are tuned @ around 4.8GHz see attached a 10s quick EM simul.
From which software is this screenshot taken? I am looking for software that can be used to create stubs like this
 

LaTeX Commands Quick-Menu:

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top