Patent ID: 7508268
Filing Date: 2009-03-24
Classification: H01L,H03F

Abstract:
1. A power amplifier comprising: an input terminal; first and second switches connected at respective first ends to the input terminal in common; a first multi-finger FET formed on a semiconductor substrate and connected at a gate thereof to a second end of the first switch; a second multi-finger FET formed on the semiconductor substrate and connected at a gate thereof to a second end of the second switch; an output terminal connected in common to drains of the first and second FETs; a first temperature detector which detects a channel temperature of the first FET; a second temperature detector which detects a channel temperature of the second FET; a third temperature detector which detects a temperature of the semiconductor substrate; a first detection circuit which detects a difference between an output of the first temperature detector and an output of the third temperature detector and converts the difference to thermoelectromotive force; a second detection circuit which detects a difference between an output of the second temperature detector and the output of the third temperature detector and converts the difference to thermoelectromotive force; and a comparator which compares outputs of the first and second detection circuits with each other to turn on one of the first and second switches and turn off the other.