How can I know for each connection in the layout shown in the picture to what pin it connects to the chip?

You know by looking at the schematic shown in the mmic or eval board datasheet.

 

Hello,In the photo below we have layout.In my board they mark Vg2 on bottom.
How can I know based on the photo below what pin is the FALSE vg2?
Thanks.

 

update:

Hello ,So I made a pin map as shown below,Is it ok?
How do you reccomend to meausre the current going threw the drain?

 

Hello,In the photo below we have layout.In my board they mark Vg2 on bottom.
How can I know based on the photo below what pin is the FALSE vg2?

Vg2 on the right side of the bottom pin header would be the wrong one as it is connected to the N.C. pin 19 and there are also no populated components on the PCB.

Vg2 (left side, top header) goes to pin 2 of the MMIC.

Hello ,So I made a pin map as shown below,Is it ok?

Yes.

How do you reccomend to meausre the current going threw the drain?

With an Ampere-meter, for instance an analog or digital multimeter in DC current position. If you have a modern power supply that has a digital V/A display with decent resolution and accuracy use that.

 

My amplifier worked but then It got burned .
I have a problem with Vdd, what could cause failure in VDD?
Video is attached.
Thanks.
20250519_125300000_iOS.MOV

 

That's very unfortunate. Sorry to hear that.

I understand the amplifier worked for a while until something happened. Can you trace your steps back to find what could be the culprit?

Setting Idd manually with Vgg1 was successful? Was Vgg1 and Idd stable at all times with no RF apllied? The sequencer worked as intended, especially switching Vgg1 between the Initial - 2V pinch-off voltage and the actual operating value? Was the amplifier power supply current limited during the test?

Did you try to go through the power on/off sequence manually, step by step (without the sequencer) to see what is happening to all the voltages and overall current?

One thing that sticks out in the video is that the RF ports were left open. I assume that was never the case during your test?

 

When tuning Vg1=-0.8V I got Id=400mA then After shutting down the biasing I noticed that the heat sink is very hot.
Then I connected to it another heat sink with silver paste.
next I just turned on the ampliyier straight away with Vg1=-0.8V( no -2V then going up to -0.8V)
I saw gain of10 dB after, then it burned.
Do you think the Heat sink was the problem?
Or maybe I was not suppose to turn th amplifier at vg1 =-0.8 straight away in the next iterations?
Thanks.

 

When tuning Vg1=-0.8V I got Id=400mA then After shutting down the biasing I noticed that the heat sink is very hot.

That's normal, the chip is working in class-A and dissipates almost 5W with a quiescent current of 400mA. An extra heatsink is certainly a good idea.

next I just turned on the ampliyier straight away with Vg1=-0.8V( no -2V then going up to -0.8V)

Unfortunately this is not good at all. The power on/off sequence from the datasheet is clear on that.
You inadvertently set the final drain current long before Vgg2 and VDD were turned on and had time to stabilize.

I mentioned in an earlier posting that GaAs (power) FETs tend to be unstable at low drain voltages. To avoid instability, you put them first in pinch-off (Vgg1 = -2 V), turn on drain voltage, wait until it stabilized and only then adjust gate voltage to the final value (Vgg1 = - 0.8 V). This makes the neccessary sequencer more complex than the amplifier itself.

Apply - 2 V only to Vgg1 and measure with an Ohm-meter across C2. If it's a short then you are probably out of luck.
You could also go through the full power on/off sequence manually and try to set some average Id value to see of it is still possible to do that. Use a current limited power supply.

 

That's normal, the chip is working in class-A and dissipates almost 5W with a quiescent current of 400mA. An extra heatsink is certainly a good idea.



Unfortunately this is not good at all. The power on/off sequence from the datasheet is clear on that.
You inadvertently set the final drain current long before Vgg2 and VDD were turned on and had time to stabilize.

I mentioned in an earlier posting that GaAs (power) FETs tend to be unstable at low drain voltages. To avoid instability, you put them first in pinch-off (Vgg1 = -2 V), turn on drain voltage, wait until it stabilized and only then adjust gate voltage to the final value (Vgg1 = - 0.8 V). This makes the neccessary sequencer more complex than the amplifier itself.

Apply - 2 V only to Vgg1 and measure with an Ohm-meter across C2. If it's a short then you are probably out of luck.
You could also go through the full power on/off sequence manually and try to set some average Id value to see of it is still possible to do that. Use a current limited power supply.

Hi, I am interested about this fact that GaAs FETs can be unstable at low drain voltages. Could you maybe share some references that discuss this? I tried searching for it but couldn't find any meaningful results.

 

What signal did you input to the amplifier??What are you using to measure the signal out of the amplifier THAT is the way to test an amplifier like this one.

Have you read and understood the application data and specifications?? Doing that is VITAL, not just EXTREMELY IMPORTANT!!
What company produced this amplifier and what company sold it to you???