I am currently making an Rf transmitter which works on 2.4GHz and the main goal is to achieve 1 watt of power at the transmitting end. I am using max2750 as my vco for the project and have made its evaluation board according to the design given in the datasheet. Now the problem which i am facing is the on the spectrum analyzer i am only seeing a single peak of 2.4GHz having an amplitude of -32dbm which is very small compare to the actual output power of -3dBm. why is that ? and what can be the solution for it? I am also attaching the picture of the hardware of the vco

 

Is an antenna connected when taking measurement?

 

The power am talking about is the output power of max2750 which is measured by a spectrum analyzer. Right now i am only measuring the power of the vco module not the whole circuit so at the moment there is no antenna attached however i will be designing a patch antenna in order to measure the 1 watt transmitting power of the Rf transmitter

 

Would it be appropriate to connect a suitable 'dummy' load resistor at the overall circuit output? ... Possibly connect the analyzer by means of a 'T' connector?

 

What are you using as a load for test. Show us your print/schematic. And test equipment connections.

 

We assume you have checked pcb pad/trace isolation and proper voltage is getting to chip.

Have you built GHz circuits before?

 

Would it be appropriate to connect a suitable 'dummy' load resistor at the overall circuit output? ... Possibly connect the analyzer by means of a 'T' connector?

Yes i am using a 50 ohm load and a T connector for the analyzer

 

What are you using as a load for test. Show us your print/schematic. And test equipment connections.

I am using a 50 ohm load cable with a t connector

 

Thus i

We assume you have checked pcb pad/trace isolation and proper voltage is getting to chip.

Have you built GHz circuits before?[/QUOT

We assume you have checked pcb pad/trace isolation and proper voltage is getting to chip.

Have you built GHz circuits before?

this is my first time building a GHz circuit . I am also in a doubt about my pcb layout because when i apply the shutdown logic gate unit voltage the power supply providing Vcc becomes short

 

Ok....thanks. Microwave frequencies used to be the voodoo of electronics. That means its voodoo to me. Although I'm quite sure there have been many improvements. With a little study and practice you should be able to master it. There are MW experts on here.....not sure how elementary they go.

MW circuits are finicky and need to be exact. Can you afford to purchase a premade board?

That might be the way to go. Especially with the oscillator. Maybe the PA board could be a first construction project?

Sorry I can't help you more. It's out of my league.

 

Ok....thanks. Microwave frequencies used to be the voodoo of electronics. That means its voodoo to me. Although I'm quite sure there have been many improvements. With a little study and practice you should be able to master it. There are MW experts on here.....not sure how elementary they go.

MW circuits are finicky and need to be exact. Can you afford to purchase a premade board?

That might be the way to go. Especially with the oscillator. Maybe the PA board could be a first construction project?

Sorry I can't help you more. It's out of my league.

I can buy the premade board but i really want to make the board myself. Anyways, thank you for looking into my problem

 

Hello,

Have a look on how the PCB of the evaluation kit looks like.

Bertus

 

Hello,

Have a look on how the PCB of the evaluation kit looks like.

Bertus

Yes i have tried following the the exact EV board when making the vco hardware

 

Hello,

Is your PCB also double sided as in the PDF?
Did you see all the spots on the component layout?



Those are via's , connections between top and bottom layer.

Bertus

 

Yes the pcb is double-sided and about the the vias there are only two holes in my pcb layout and they have been filled with copper. Someone told me that the true response can also come with less number of via but if not they can be drilled later in the layout. So can less number of vias be the reason for a very low output power ?

 

So can less number of vias be the reason for a very low output power ?

It's possible.
I suggest you stop talking to this "someone" since he apparently does not know what he is talking about.

 

I am using a 50 ohm load cable with a t connector

I'm looking into this device myself. My Spectrum Analyzer only goes to 1.3 GHz, so I couldn't use it directly. However, my Spectrum Analyzer IS a 50 Ohm load so I wouldn't use a Tee connector.

 

As I came upon this post, I think it is relevant. It's not about my immediate problem, but as it had no good answer, perhaps my input is helpful.