Stable, Closed-Loop, Automatic Power Control for RF Applications

AN-1507, Application note provides closed-loop, automatic power control using a variable gain amplifier (VGA), ADL5330, and a log detector, AD8318. Due to the high temperature stability of the AD8318, this circuit provides stability over temperature because the AD8318 radio frequency (RF) detector ensures the same level of temperature stability at the output of the ADL5330 VGA. The addition of the log amp detector converts the ADL5330 from an open-loop variable gain amplifier to a closed-loop output power control circuit