Apparatus and methods for overload protection of radio frequency amplifiers

Abstract

Radio frequency (RF) amplifiers with overload protection are provided herein. In certain configurations, an RF amplifier system includes an RF amplifier that receives an RF signal from an input terminal. The RF amplifier includes an amplification field-effect transistor (FET) having a gate that receives the RF signal, and a degeneration circuit connected between a source of the amplifier FET and a ground voltage. The RF amplifier system further includes an electrostatic discharge protection circuit including a plurality of protection diodes electrically connected in series between the input terminal and the ground voltage, and a detector having an input connected along an electrical path through the plurality of protection diodes and an output that generates a detection signal operable to control an amount of degeneration provided by the degeneration circuit.

What is claimed is: 
     
         1 . A radio frequency amplifier system comprising:
 an input terminal configured to receive a radio frequency signal;   a radio frequency amplifier configured to amplify the radio frequency signal, the radio frequency amplifier including an amplification field-effect transistor having a gate configured to receive the radio frequency signal, and a degeneration circuit connected between a source of the amplifier field-effect transistor and a ground voltage; and   an electrostatic discharge protection circuit including a first plurality of protection diodes electrically connected in series between the input terminal and the ground voltage, and a detector having an input connected along an electrical path through the first plurality of protection diodes and an output configured to generate a detection signal operable to control an amount of degeneration provided by the degeneration circuit.   
     
     
         2 . The radio frequency amplifier system of  claim 1  wherein the first plurality of protection diodes includes a first protection diode having an anode coupled to the ground voltage and a cathode coupled to the input of the detector, and a second protection diode having an anode coupled to the input of the detector and a cathode coupled to the input terminal. 
     
     
         3 . The radio frequency amplifier system of  claim 1  wherein the first plurality of protection diodes includes at least three protection diodes in series between the ground voltage and the input terminal. 
     
     
         4 . The radio frequency amplifier system of  claim 1  wherein the first plurality of protection diodes are connected in series from anode to cathode between the ground voltage and the input terminal, the electrostatic discharge protection circuit further including a second plurality of protection diodes connected in series from anode to cathode between the input terminal and the ground voltage. 
     
     
         5 . The radio frequency amplifier system of  claim 1  wherein the detection signal is operable to increase the amount of degeneration provided by the degeneration circuit in response to the detector detecting an overload condition. 
     
     
         6 . The radio frequency amplifier system of  claim 1  wherein the radio frequency amplifier includes a capacitor connected in series between the input terminal and the gate of the amplification field-effect transistor. 
     
     
         7 . The radio frequency amplifier system of  claim 1  wherein the degeneration circuit includes a degeneration inductor and a switch in series between the source of the amplification field-effect transistor and the ground voltage, and a control buffer configured to control the switch based on the detection signal. 
     
     
         8 . The radio frequency amplifier system of  claim 7  wherein the control buffer is powered by the detection signal. 
     
     
         9 . The radio frequency amplifier system of  claim 8  wherein the control buffer includes an input configured to receive a digital control signal for toggling the switch. 
     
     
         10 . A mobile phone comprising:
 an antenna configured to receive a radio frequency signal; and   a front-end system configured to receive the radio frequency signal at an input terminal and including a radio frequency amplifier configured to amplify the radio frequency signal, the radio frequency amplifier including an amplification field-effect transistor having a gate configured to receive the radio frequency signal, and a degeneration circuit connected between a source of the amplifier field-effect transistor and a ground voltage, the front-end system further including an electrostatic discharge protection circuit including a first plurality of protection diodes electrically connected in series between the input terminal and the ground voltage, and a detector having an input connected along an electrical path through the first plurality of protection diodes and an output configured to generate a detection signal operable to control an amount of degeneration provided by the degeneration circuit.   
     
     
         11 . The mobile phone of  claim 10  wherein the first plurality of protection diodes includes a first protection diode having an anode coupled to the ground voltage and a cathode coupled to the input of the detector, and a second protection diode having an anode coupled to the input of the detector and a cathode coupled to the input terminal. 
     
     
         12 . The mobile phone of  claim 10  wherein the first plurality of protection diodes includes at least three protection diodes in series between the ground voltage and the input terminal. 
     
     
         13 . The mobile phone of  claim 10  wherein the first plurality of protection diodes are connected in series from anode to cathode between the ground voltage and the input terminal, the electrostatic discharge protection circuit further including a second plurality of protection diodes connected in series from anode to cathode between the input terminal and the ground voltage. 
     
     
         14 . The mobile phone of  claim 10  wherein the degeneration circuit includes a degeneration inductor and a switch in series between the source of the amplification field-effect transistor and the ground voltage, and a control buffer configured to control the switch based on the detection signal. 
     
     
         15 . The mobile phone of  claim 14  wherein the control buffer is powered by the detection signal. 
     
     
         16 . The mobile phone of  claim 15  wherein the control buffer includes an input configured to receive a digital control signal for toggling the switch. 
     
     
         17 . A packaged module comprising:
 a packaging substrate; and   a semiconductor die attached to the packaging substrate, the semiconductor die including an input terminal and a radio frequency amplifier configured to amplify a radio frequency signal received from the input terminal, the radio frequency amplifier including an amplification field-effect transistor having a gate configured to receive the radio frequency signal, and a degeneration circuit connected between a source of the amplifier field-effect transistor and a ground voltage, the semiconductor die further including an electrostatic discharge protection circuit including a first plurality of protection diodes electrically connected in series between the input terminal and the ground voltage, and a detector having an input connected along an electrical path through the first plurality of protection diodes and an output configured to generate a detection signal operable to control an amount of degeneration provided by the degeneration circuit.   
     
     
         18 . The packaged module of  claim 17  wherein the degeneration circuit includes a degeneration inductor and a switch in series between the source of the amplification field-effect transistor and the ground voltage, and a control buffer configured to control the switch based on the detection signal. 
     
     
         19 . The packaged module of  claim 18  wherein the control buffer is powered by the detection signal. 
     
     
         20 . The packaged module of  claim 19  wherein the control buffer includes an input configured to receive a digital control signal for toggling the switch.