LMH6401: Single ended to differential conversion with no gain and low noise figure

Brandon Buckley

Part Number: LMH6401
Other Parts Discussed in Thread: THS4131, , LMH5401

I need to convert a single ended signal to a differential signal. However, I do not require gain. Additionally, this is a highly sensitive measurement, so low noise figure is critical. The only SE to differential converters I can find are amplifiers with quite a bit of gain. With the gain, I end up having to add attenuation (both before and after amplification), which greatly reduces SNR.

Is there a SE to differential converter with no gain and low noise figure?

over 4 years ago

0 Jacob Freet over 4 years ago

TI__Expert 7875 points

Hi,

I would suggest that you could look at the THS4131 as an option. This has an input referred noise of 1.3nV/rtHz. To figure out the exact noise figure I need to know the impedance of your source. Is it 50 Ohms?

Regards,

0 Brandon Buckley over 4 years ago in reply to Jacob Freet

Prodigy 135 points

Hi Jacob,

Thank you for the great suggestion. I see that the gain is tunable and can be set to 1 if desired. That is exactly what we are looking for.

I should have given more information in my question though, I apologize.

We are indeed operating at 50 Ohms. However, the THS4131 unfortunately does not have enough bandwidth. Ours is a broadband application, DC to 6.5 GHz. Sorry for not clarifying that up front. Are there similar components with the bandwidth we need?

Thanks!

-Brandon

0 Michael Steffes over 4 years ago in reply to Brandon Buckley

Guru 47535 points

Are you seriously DC to 6.5GHz - that DC part is hard in a 6.5GHz high end - and normally, you need some gain to get a low input noise figure. There are some specialized modules that do that span, but virtually the entire 6.5GHz RF amplifier world is AC coupled.

0 Michael Steffes over 4 years ago in reply to Michael Steffes

Guru 47535 points

found one, but I am sure there are a few others,

https://www.rfmw.com/Products/Detail/MMA053AA-Microsemi-Corp/618501/

0 Jacob Freet over 4 years ago in reply to Brandon Buckley

TI__Expert 7875 points

Hi Brandon,

The LMH5401 or LMH6401 are going to be the closest devices we have.

Regards,

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LMH6401: Single ended to differential conversion with no gain and low noise figure