Greetings wahooburger (sounds a lot like my nane
Power control is implemented in the transceiver. The transceiver output typically feeds directly into the PA. Most WLAN PAs now have a built-in power detector that feeds back to the transceiver. Bias control on the PAs is used to achieve best performance (EVM, harmonics, Psat, etc.), but the gain of the PA is usually fixed by design (about 30 dB for a 3-stage device).
SiGe, RFMD, Fairchild, Gatax, Tavanza, RFIC, RF Solutions, Skyworks, and many others make WLAN PAs. You can get scads of info from their websites.
- Kirt Blattenberger