ADS4242: Ads4242

Yinon Kares

Part Number: ADS4242
Ads 4242 has a 2 Vpp analog input condition. For a 50 ohm input impedance it’s go to PFs of 10 dBm. It’s true to assume that by using 1:N transformer I can reduce the PFs by factor of N^2 ? If it’s true, it’s cause also to reduce ADC absolute noise floor (dBm value) according to ADC SNR spec (given in dBFS) ? Regards, Yinon

over 4 years ago

0 jim s over 4 years ago

TI__Guru* 91947 points

Yinon,

See if the attached document helps explain this.

Regards,

Jim

RF source power with internal resistance as 50ohms.docx

0 Nir Flysher over 4 years ago in reply to jim s

TI__Expert 3287 points

Hi Jim,

One little question to carify the NF after 1:1 ballun vs 1:N on the document you've attached.

The NF improvement will not be achieved by the transformer right ? (after all it is a passive component)
It will increase/decrease both the signal and the noise at the same ratio.

It will be achieved due to the reason that the customer will now be able to use lower voltage on the transformer input and hence will need to add less gain to the received signal (each gain stage adds more noise).

Hence the use of a higher ratio transformer itself doesn't improve the NF.

Would you agree ?

Regards,

Nir.

0 jim s over 4 years ago in reply to Nir Flysher

TI__Guru* 91947 points

Nir,

I would agree with you.

Happy New Year!

Jim

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ADS4242: Ads4242