Trying to understand the SDR Play Specs

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Player
Posts: 2
Joined: Mon Oct 12, 2015 4:26 am

Trying to understand the SDR Play Specs

Postby Player » Mon Oct 12, 2015 4:34 am

Hi SDR Play,

I'm trying to understand where the MGA-68563 LNA and the Mirics chip LNA's come into play.

Is the MGA-68563 active all the time for signals over 60 MHz? In the SDR Play config screen when it says LNA Off/On, is this referring the the MGA-68563, or the LNA within the Mirics chips?

If the IIP3 calculation in the datasheet referring to the MSI001 chip only, or does it include the MGA-68563 as well?
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jon
Posts: 293
Joined: Tue Jan 06, 2015 10:48 am

Re: Trying to understand the SDR Play Specs

Postby jon » Mon Oct 12, 2015 7:28 am

Perhaps this explains things regarding how the two different amps are used across the bands. Please note that the exact bands in the VHF region have changed slightly since this document was written. http://www.sdrplay.com/docs/SDRplay_AGC ... e_r2p2.pdf
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Player
Posts: 2
Joined: Mon Oct 12, 2015 4:26 am

Re: Trying to understand the SDR Play Specs

Postby Player » Mon Oct 12, 2015 8:07 am

Thanks, so from what i've gathered, the LNA being referred to in those and other documents is the LNA that is internal to the MSI001 chip? And the internal LNA of the MSI001 chip is turned on or off depending on the gain reduction setting.

Then as I understand it the MGA-68563 LNA is always on, and cannot be turned off?

Edit: also still unsure if the figures in the datasheet are for the whole sdrplay, including the MGA-68563, or just the MSI001. For example if i'm doing a noise figure calculation, do I include the MGA-68563 LNA as an extra stage, or is it already lumped in with those published figures?
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Tech_Support
Posts: 202
Joined: Mon Jun 01, 2015 7:00 pm

Re: Trying to understand the SDR Play Specs

Postby Tech_Support » Mon Oct 12, 2015 8:54 am

Dear Player,
You are correct that the switchable LNA referred to in the documentation is the internal LNA on the MSi001. Also the external pre-amp that is designed to overcome the insertion loss of the RF pre-selection filters is always on. However, this pre-amp is not used in the HF bands. It is only used above 60 MHz.

Sincerely

SDRplay Tech_Support
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