Integrated rf limiter

Abstract

A limiter circuit is integrated into an RF power amplifier. The limiter circuit automatically starts adding attenuation at the input of the RF power amplifier after a predetermined input power level threshold is exceeded, thereby extending the safe input drive level to protect the amplifier. In a preferred embodiment of the invention, the limiter circuit is implemented using a pseudomorphic high electron mobility transistor (PHEMT) device or a metal semiconductor field effect transistor (MESFET) device. Diode connected transistors or Schottky diodes may also be used in the limiter circuit.

1 - 24 . (canceled) 
     
     
         25 . A power amplifier module comprising:
 a signal input;   a power amplifier stage of a first power amplifier, the power amplifier stage of the first power amplifier including a first transistor; and   a first limiter connected between the signal input and the power amplifier stage of the first power amplifier, the first limiter including at least a first pseudomorphic high electron mobility transistor connected to a base of the first transistor and a first diode connected to a collector of the first transistor.   
     
     
         26 . The power amplifier module of  claim 25  wherein the first transistor is a heterojunction bipolar transistor. 
     
     
         27 . The power amplifier module of  claim 25  wherein the power amplifier stage of the first power amplifier is formed in a III-V semiconductor material. 
     
     
         28 . The power amplifier module of  claim 25  wherein the first limiter further includes a second diode connected in series to the first diode. 
     
     
         29 . The power amplifier module of  claim 25  wherein the first diode is implemented by a second pseudomorphic high electron mobility transistor. 
     
     
         30 . The power amplifier module of  claim 25  wherein the first diode is implemented by a metal-semiconductor field-effect transistor. 
     
     
         31 . The power amplifier module of  claim 25  wherein the first diode is a Schottky barrier diode. 
     
     
         32 . The power amplifier module of  claim 25  further comprising a power amplifier stage of a second power amplifier, the power amplifier of the second power amplifier including a second transistor, and the second power amplifier configured to support a different power level than the first power amplifier. 
     
     
         33 . The power amplifier module of  claim 32  further comprising a second limiter connected between the signal input and the power amplifier stage of the second power amplifier. 
     
     
         34 . The power amplifier module of  claim 33  wherein the second limiter includes at least a second pseudomorphic high electron mobility transistor connected to a base of the second transistor and a second diode connected to a collector of the second transistor. 
     
     
         35 . The power amplifier module of  claim 32  further comprising a switch configured to select between a first path associated with the first power amplifier and a second path associated with the second power amplifier. 
     
     
         36 . The power amplifier module of  claim 25  wherein the first limiter circuit is configured to attenuate a signal received at the signal input when an input power level satisfies a threshold. 
     
     
         37 . The power amplifier module of  claim 25  wherein the first limiter further includes a direct current blocking capacitor connected to the first pseudomorphic high electron mobility transistor. 
     
     
         38 . A wireless device comprising:
 an antenna; and   a power amplifier module including a signal input, a power amplifier stage of a first power amplifier, and a first limiter, the power amplifier stage of the first power amplifier including a first transistor, and the first limiter connected between the signal input and the power amplifier stage of the first power amplifier, and including at least a first pseudomorphic high electron mobility transistor connected to a base of the first transistor and a diode connected to a collector of the first transistor.   
     
     
         39 . The wireless device of  claim 38  wherein the wireless device is a cellular phone. 
     
     
         40 . The wireless device of  claim 38  wherein the diode is implemented by a second pseudomorphic high electron mobility transistor, is implemented by a metal-semiconductor field-effect transistor, or is a Schottky barrier diode. 
     
     
         41 . The wireless device of  claim 38  wherein the power amplifier module further includes a power amplifier stage of a second power amplifier and a second limiter connected between the signal input and the power amplifier stage of the second power amplifier, the power amplifier of the second power amplifier including a second transistor, and the second power amplifier configured to support a different power level than the first power amplifier. 
     
     
         42 . The wireless device of  claim 41  wherein the second limiter includes at least a second pseudomorphic high electron mobility transistor connected to a base of the second transistor and a second diode connected to a collector of the second transistor. 
     
     
         43 . The wireless device of  claim 41  wherein the power amplifier module further includes a switch configured to select between a first path associated with the first power amplifier and a second path associated with the second power amplifier. 
     
     
         44 . The wireless device of  claim 38  wherein the first limiter circuit attenuates a signal received at the signal input when an input power level satisfies a threshold.