Apparatus and methods for adaptive power amplifier biasing

A mobile device comprising:

• a transceiver configured to generate a radio frequency input signal;
• and
• a front end system including a power amplifier configured to amplify the radio frequency input signal and biased by a bias signal, and a detector configured to generate a baseband detection signal based on the radio frequency signal and to process the baseband detection signal to generate a high pass detection signal and a low pass detection signal, the detector further configured to generate a bandwidth signal based on a comparison of the high pass detection signal to the low pass detection signal, the front end system further including a power amplifier bias control circuit configured to generate the bias signal based on the bandwidth signal.