LMX2595EVM: Output Power Issue

user6326811

Part Number: LMX2595EVM
Other Parts Discussed in Thread: LMX2595

Hi all,

I can not get the output power values as datasheet states.
I always get output power less than expected.
I use TICS software to program LMX2595 Evaluation board.
I think there is something wrong with my settings.

As an example, I attached the TICS software screenshots for 7GHz output.
The datasheet says I should get around 9dBm for inductive pull-up. However I get around 5dBm at 7GHz. I tried other frequencies but output power is always less than expected.
Can you please check the attachments and tell me if there is something wrong ?

Thanks in advance.

over 5 years ago

0 Noel Fung over 5 years ago

TI__Guru** 108330 points

Hi There,

We were using a different board with very short RF output trace length to measure the output power. The regular EVM will has less output power due to layout.

0 user6326811 over 5 years ago in reply to Noel Fung

Prodigy 50 points

Hi,

How much less power will the EVM have?

0 Vibhu Vanjari over 5 years ago in reply to user6326811

TI__Genius 11900 points

Hello,

5 dbM is in the right ball-park, this will change from frequency to frequency. Another thing you can check is sometimes adjusting the tightness on the SMA connectors might help.

If you use doubler setting DBLR_IBIAS_CTRL1 to 3115 will help a little.

Thanks,

Vibhu

0 user6326811 over 5 years ago in reply to Vibhu Vanjari

Prodigy 50 points

Hi Vibhu,

I've measured the output power from frequency 3GHz to 15GHz without doubler and OUTPUT_PWR = 50.

I use single-ended port B output. The unused pin of port B is terminated via 50ohm load. The unused pin of the oscillator input is not terminated.

I've set capcode and amplitude in accordance to VCO Core, as the datasheet describes.

The connectors are quite tight, I use a torque screw.

I've attached the result below.

Especially for the frequencies 13,14 and 15GHz the power goes below 0dBm whereas the datasheet shows it should be around 7dBm.

Do you confirm the results below are acceptable ?

Thanks in advance.

0 Vibhu Vanjari over 5 years ago in reply to user6326811

TI__Genius 11900 points

Hello,

This is looks fine.

On a side note, can you confirm you see the correct frequency and lock detect reads lock?

Thanks,

Vibhu

0 user6326811 over 5 years ago in reply to Vibhu Vanjari

Prodigy 50 points

Hello Vibhu,
Thanks for your help.

Yes, I see the correct frequency on spectrum analyzer and the lock-detect led is turned-on.

0 Vibhu Vanjari over 5 years ago in reply to user6326811

TI__Genius 11900 points

Hello,

Thanks for confirming.

-Vibhu

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LMX2595EVM: Output Power Issue