LMX2492EVM: Questions on details of the evaluation board

Isaac Fenta

Part Number: LMX2492EVM
Other Parts Discussed in Thread: LMX2492,

I am trying to find an oscillator that can output 10GHz signal consistently. I found the LMX2492 on digikey, and it seems that it would be a good solution for me. However, I do have a few questions before I purchase the evaluation board to test it:

1. What is the impedance of the circuit so I can get the correct antenna, and design a new antenna in the future. Do you provide antennas for this evaluation board?

2. Where do I get the software to program the board? I saw that software is needed, but I couldn't find a link to download it; will a CD of some sort be provided in the evaluation kit?

3. What is the output power of the board at 10 GHz; is there a minimum signal (frequency and power) I have to put in first?

Thanks!

over 8 years ago

0 Noel Fung over 8 years ago

TI__Guru** 108090 points

Hi Isaac,

You can find all the information, including EVM user's guide; software tool and simulation tool in ti.com.
No, we do not provide antenna for the board.
Typical output power at RF/2 port is 3dBm.

0 Isaac Fenta over 8 years ago in reply to Noel Fung

Intellectual 480 points

Hi Noel,

Thank you for your response. Do you happen to know the impedance of the board so I can get the correct antenna? It will help speed up our prototyping process. Thank you!

0 Noel Fung over 8 years ago in reply to Isaac Fenta

TI__Guru** 108090 points

Hi Isaac,
The output of the board is taken from the VCO output via a 6 dB T-attenuator, so the impedance is 50 ohm. However, I don't think it is appropriate to attach an antenna directly from the output of the board because the pulling effect of the antenna may adversely affect the VCO performance. You may need at least one (preferably a couples of) amplifiers between the board and the antenna.

0 Isaac Fenta over 8 years ago in reply to Noel Fung

Intellectual 480 points

Hi Noel,

Do you have any recomendations for amplifiers to be used between the antenna and board? Thanks!

0 Noel Fung over 8 years ago in reply to Isaac Fenta

TI__Guru** 108090 points

Hi Isaac,

I am afraid I don't have recommendation on this, I think TI do not have this kind of amplifiers.

0 Isaac Fenta over 8 years ago in reply to Noel Fung

Intellectual 480 points

Hi Noel,

I found an om amp on digikey that is from TI that has -3db Bandwidth at 12 GHz (MPN: ONET8501PRGTR); I was thinking of making it like a voltage follower to isolate the signal. Can this one work? If not, do you know of a general amplification design I can look toward, or who I can speak to on this matter? Thank you!

0 Noel Fung over 8 years ago in reply to Isaac Fenta

TI__Guru** 108090 points

Hi Isaac,

That is a limiting amplifier for network data usage, I am not quite sure how will it performance if the input is a clock signal instead of data signal. Maybe you could raise a question in the related forum: e2e.ti.com/.../10

0 Isaac Fenta over 7 years ago in reply to Noel Fung

Intellectual 480 points

Hi Noel,

Thanks, I went over to that forum and it is helping. I was wondering if instead of attaching the LMX2492EVM to an antenna, that I attached it to a pHEMT FET (ie https://www.digikey.com/product-detail/en/cel/CE3512K2/CE3512K2-ND/6165442

0 Brian Wang over 7 years ago in reply to Isaac Fenta

TI__Expert 8505 points

Noel,

This was a thread that split out so attaching back Isaac's comments to this original thread:

"Before I asked if I could connect an antenna directly to the eval board, but now I am thinking of connecting a pHEMT FET to it instead. I was told to put an amplifier to the eval board before the antenna, so this could be used as an amplifier in a way. Do you know if this pHEMT FET (www.digikey.com/.../6165442) will work with it? Im thinking of connecting the gate to the LMX2492, and connecting the source and drain to a power source. Let me know. Thanks!"

0 Noel Fung over 7 years ago in reply to Brian Wang

TI__Guru** 108090 points

Hi Isaac,
I think you may need to design the matching and biasing circuitry for this FET.

0 Isaac Fenta over 7 years ago in reply to Noel Fung

Intellectual 480 points

Hi Noel,

I have someone designing an impedance matching circuit for the antenna that will be connected to this device. I was wondering if you could tell me if this plan will work, or if there are other things I should consider before purchasing. Thanks!

0 Noel Fung over 7 years ago in reply to Isaac Fenta

TI__Guru** 108090 points

Hi Isaac,

Did you mean some matching networks between the EVM, the FET and the antenna?

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LMX2492EVM: Questions on details of the evaluation board