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

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?

Vivian Gao：

您好

我们帮您进一步咨询，请等待此链接的回复。

e2e.ti.com/…/afe5818-why-does-the-afe5818-use-an-lna-vcat-and-pga-in-sequence-instead-of-integrating-the-functions-into-a-single-stage