Dual band variable gain amplifier

[Johannah]

Good day Everyone!

I'm currently studying about dual band variable gain amplifier for wifi which means the 2.4GHz and 5GHz. This block is part of the AGC. However, I believe that this frequency will be down-converted since this block is after the mixer in the receiver. I don't know what is the usual LO frequency for wifi. Does anyone know what is the frequency that I will be targeting in my VGA design? Also has anyone has a reference for dual-band VGA architectures. So far, i haven't seen any.

Thanks a lot for those who will help me.

 

[vfone]

To answer to your questions you have to know what receiver type is used by the system. Super-heterodyne (unlikely), direct conversion, low-IF, etc.
If the VGA is placed after the mixer, there is no "dual-band VGA". In both situations (2.4GHz and 5GHz) the VGA's should be the same.

 

[Johannah]

Thank you for your reply, sir. Can you recommend any book or reference for designing a VGA? Actually, this VGA is for the transceiver and I'm a newbie in RF design.