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AFE5818: Why does the AFE5818 use an LNA, VCAT, and PGA in sequence, instead of integrating the functions into a single stage?

Jiahui Gao
Expert 3720 points
Part Number: AFE5818

Tool/software:

Hi team，

I'm working with the AFE5818, which includes a Low Noise Amplifier (LNA), a Voltage-Controlled Attenuator (VCAT), and a Programmable Gain Amplifier (PGA). I'm curious why the signal chain is designed to first amplify (LNA), then attenuate (VCAT), and finally amplify again (PGA). Wouldn't this introduce additional noise? Why not integrate all functions into a single stage to avoid extra noise?

Thanks & Best regards，

Jiahui

  • +1
    TI__Expert 5955 points

    This architecture is chosen to balance between power and performance . Usually initial stage will be low noise stage where you need to burn lot of power. And to have lot of gain range there is very difficult . Because of this multiple stage architecture is choosen,