THS7002: Use PGA without LNA

user4993800

Part Number: THS7002

Hi,

Can the PGA be used without the LNA? That is, can I only provide power to the PGA section and ground the power inputs for the LNA? My power budget is tight and I cannot afford the quiescent current draw of the LNA, but the datasheet says the supply voltage for the PGA must be less than the LNA, so I'm worried I might not be able to do so. Thanks.

over 5 years ago

0 Sima Jalaleddine over 5 years ago

TI__Mastermind 25795 points

Hello,

From the schematic in the datasheet, it would look like you would be able to power the PGA without needing to power the LNA. However, you do bring up a valid concern when it comes to that statement. I will have to look into this, and will have an update for you by the end of this week. What is the power supply range of your application (to the PGA section)?

Thank you,

Sima

0 user4993800 over 5 years ago in reply to Sima Jalaleddine

Prodigy 30 points

Hi Sima, thanks for the help. For my application, I am intending to use +/-5V.

0 Sima Jalaleddine over 5 years ago in reply to user4993800

TI__Mastermind 25795 points

Hello,

Unfortunately, you will not be able to power the PGA without powering the preamplifier (LNA). We were able to pull up the design schematics for this part, the power supplies between the two amplifiers share protection diodes. It turns out that the ESD protection circuitry is all based on the preamplifier powering on.

Thank you,

Sima

0 user4993800 over 5 years ago in reply to Sima Jalaleddine

Prodigy 30 points

Hi Sima,

Understood. Thanks for looking into it for me.

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THS7002: Use PGA without LNA