Patent ID: 7786805
Filing Date: 2010-08-31
Classification: H03F,H03G

Abstract:
1. A power amplifier module, comprising a power amplifier circuit having a power supply regulated output power level; a power supply transistor coupled to the power amplifier circuit and operable to control a power supply to the power amplifier circuit in response to a drive signal, wherein the power supply transistor is a Field Effect Transistor; a drive circuit coupled to the power supply transistor and operable to generate the drive signal in response to a power level input signal; a detection circuit for determining an operating characteristic of the power supply transistor; and a control circuit coupled to the drive circuit and operable to control the drive signal in response to the operating characteristic; wherein the control circuit is operable to control the drive signal to substantially prevent the power supply transistor from entering a FET linear region operating state; and the detection circuit comprises a sense transistor operable to detect a drain- gate voltage of the power supply transistor; the sense transistor conducting current if the power supply transistor enters a FET linear region of operation and if a drain-source voltage of the power supply transistor is below a gate-source voltage minus a threshold voltage of the power supply transistor; and the control circuit is operable to control the drive signal in response to the current.