Apparatus and methods for protecting radio frequency amplifiers from overdrive

A method of overdrive protection of a radio frequency amplifier, the method comprising:

• providing amplification to a radio frequency signal using a first amplification stage and a second amplification stage that is subsequent to the first amplification stage in a signal path, the first amplification stage including a first stage field-effect transistor, and the second amplification stage including a second stage field-effect transistor and a gate-to-drain feedback circuit electrically connected between a gate and a drain of the second stage field-effect transistor;
• detecting an overdrive condition of the radio frequency amplifier based on sensing a drain current of the first stage field-effect transistor;
• and
• decreasing an impedance of the gate-to-drain feedback circuit in response to detecting the overdrive condition such that a gain of the second stage field-effect transistor is reduced.

A wireless device comprising:

• a transceiver configured to generate a radio frequency signal;
• a power amplifier including a plurality of power amplifier stages arranged in a cascade, the plurality of power amplifier stages configured to amplify the radio frequency signal and including a first amplification stage and a second amplification stage that is subsequent to the first amplification stage in a signal path, the first amplification stage including a first stage field-effect transistor, and the second amplification stage including a second stage field-effect transistor and a gate-to-drain feedback circuit electrically connected between a gate and a drain of the second stage field-effect transistor;
• and
• an overdrive detection circuit configured to sense a drain current of the first stage field-effect transistor to detect when an overdrive condition is present, the overdrive detection circuit further configured to decrease an impedance of the gate-to-drain feedback circuit in response to detection of the overdrive condition such that a gain of the second stage field-effect transistor is reduced.