Impedance transformation circuit and overload protection for low noise amplifier

Abstract

Aspects of this disclosure relate to an impedance transformation circuit and overload protection for a low noise amplifier. A low noise amplifier can include a first inductor, an amplification circuit configured to amplify a radio frequency signal, and a second inductor magnetically coupled to the first inductor to provide negative feedback to linearize the low noise amplifier. A switch can be coupled to the amplification circuit of the low noise amplifier. An overload protection circuit can adjust an impedance of the switch based on a signal level associated with the radio frequency signal to provide overload protection for the low noise amplifier.

1 . (canceled) 
     
     
         2 . A low noise amplifier system comprising:
 a low noise amplifier including an input inductor, an amplification circuit configured to receive a radio frequency signal by way of the input inductor and to amplify the radio frequency signal, and a degeneration inductor magnetically coupled to the input inductor to provide negative feedback;   a switch coupled to the amplification circuit of the low noise amplifier; and   an overload protection circuit configured to detect that a signal level associated with the radio frequency signal indicates an overload condition and to cause an impedance of the switch to be increased in response to detecting that the signal level associated with the radio frequency signal indicates the overload condition.   
     
     
         3 . The low noise amplifier system of  claim 2  further comprising a feedback enable circuit configured to receive an overload protection signal from the overload protection circuit and to provide a switch control signal to a control input of the switch. 
     
     
         4 . The low noise amplifier system of  claim 3  further comprising a digital control circuit configured to selectively turn on the feedback enable circuit based on a state of one or more digital control signals. 
     
     
         5 . The low noise amplifier system of  claim 2  wherein the overload protection circuit is configured to provide a feedback signal to an analog control input of the switch. 
     
     
         6 . The low noise amplifier system of  claim 2  wherein the overload protection circuit includes a detector and an error amplifier, the detector is configured to generate a detection signal representative of the signal level associated with the radio frequency signal, and the error amplifier is configured to receive the detection signal. 
     
     
         7 . The low noise amplifier system of  claim 2  wherein the switch is in series with the input inductor. 
     
     
         8 . The low noise amplifier system of  claim 2  wherein the switch is in series with the degeneration inductor. 
     
     
         9 . The low noise amplifier system of  claim 2  wherein the low noise amplifier further includes a series inductor in series with the input inductor. 
     
     
         10 . The low noise amplifier system of  claim 9  wherein the low noise amplifier further includes a direct current blocking capacitor, the series inductor and the input inductor being electrically coupled between the direct current blocking capacitor and the amplification circuit. 
     
     
         11 . The low noise amplifier system of  claim 2  wherein the amplification circuit includes an amplification transistor configured to receive the radio frequency signal and a cascode transistor in series with the amplification transistor. 
     
     
         12 . The low noise amplifier system of  claim 2  wherein the low noise amplifier, the switch, and the overload protection circuit are implemented on a single semiconductor die. 
     
     
         13 . The low noise amplifier system of  claim 12  wherein the single semiconductor die is a silicon-on-insulator die. 
     
     
         14 . A wireless communication device comprising:
 an antenna configured to receive a radio frequency signal;   a front end system including a low noise amplifier that includes an input inductor, an amplification circuit configured to receive the radio frequency signal by way of the input inductor and to generate an amplified radio frequency signal, and a degeneration inductor magnetically coupled to the input inductor to provide negative feedback; a switch electrically coupled to the amplification circuit; and an overload protection circuit configured to cause an impedance of the switch to be increased in response to detecting that a signal level associated with the low noise amplifier indicates an overload condition; and   a transceiver configured to downconvert the amplified radio frequency signal.   
     
     
         15 . The wireless communication device of  claim 14  wherein the radio frequency front end is a wireless personal area network system configured to process wireless personal area network signals. 
     
     
         16 . The wireless communication device of  claim 15  further comprising a second antenna and a second radio frequency front end electrically coupled to the second antenna. 
     
     
         17 . The wireless communication device of  claim 14  wherein the radio frequency front end further includes a bypass path, the switch includes a first throw electrically coupled to the input inductor, and the switch includes a second throw electrically coupled to the bypass path. 
     
     
         18 . The wireless communication device of  claim 14  wherein the radio frequency front end further includes a power amplifier, the switch includes a first throw electrically coupled to the input inductor, and the switch includes a second throw electrically coupled to the power amplifier. 
     
     
         19 . A method of overload protection for a low noise amplifier, the method comprising:
 receiving a radio frequency signal at an amplification circuit of a low noise amplifier by way of an input inductor;   amplifying the radio frequency signal with the amplification circuit;   providing negative feedback to linearize the amplification circuit with a degeneration inductor magnetically coupled to the input inductor;   detecting that a signal level associated with the radio frequency signal is indicative of an overload condition; and   increasing an impedance of a switch coupled to an amplification circuit in response to the detecting to thereby provide overload protection.   
     
     
         20 . The method of  claim 19  wherein increasing the impedance of the switch attenuates the radio frequency signal received at the amplification circuit. 
     
     
         21 . The method of  claim 19  wherein increasing the impedance of the switch reduces the gain of the low noise amplifier.