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RF-Amplifire Path with to high Attenuation

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Junior Member level 1
Jul 9, 2012
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RF-Amplifier Path with to high Attenuation


i desing't a Lo amplifier path for 16 GHz.

I have a 4 GHz Rf-source. This soure multiplied with an aktive Frequenz Mulitplier after the Multiplier i should have 0dBm.
After the Multiplierer ist a Filter, an amplifier , a Filter and an Amplifire. At the end of This path i should have a Level about 13dBm but I have a level about - 20dbm.

I already use the Filter on another Board this should Work. And the amplifier work also on a Eval Board. The amplifier get the Current, Voltage they need and show an P1dB Compression Point.

What else can be the Problem on the Lo Path?

Have somebody a hint for me?
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It's not easy to make a diagnosis on the basis of these few informations. I suppose you used impedance controlled microstrip. A loss of about 30 dB could suggest a broken component along the path.

Have you the possibility to perform measurements at the output of each stage (multiplier, filter, etc.) in order to understand where the loss is located ?

Just as an additional hint I can suggest you to check the ground path (ground plane and vias), it's usually very critical.

Hey albbg!

Thx for the fast answer! Yes i use Impedance controlled microstripline on Rogers4003 Material!

This was also my frist suggestion, but I have the Problem on two different Boards and I already change all critical Componets on the Board!

This is very difficult I have no plugs between the Stages, only at the the end of the path.

I already tried to mesure the level beween the Stages with soldered RF-Cabels but I cant mesure level right, I Only see that the Amplifire has an P1dB-Compression point.

The ground plane and the vias look pretty good! how can i mesure the ground Path?

When I said to check the ground plane I ment to verify that many vias have been placed very close to the ground pins of the active components.
What you exactly mean with the sentence "I Only see that the Amplifire has an P1dB-Compression point" ? It is not clear to me.

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