Apparatus and methods for envelope tracking systems with automatic mode selection

A wireless device comprising:

• a transceiver configured to generate a radio frequency signal and an envelope signal corresponding to an envelope of the radio frequency signal;
• a power amplifier configured to provide amplification to the radio frequency signal and to receive power from a power amplifier supply voltage;
• and
• an envelope tracker configured to generate the power amplifier supply voltage based on the envelope signal, the envelope tracker including a DC-to-DC converter, an error amplifier, a signal bandwidth detection circuit configured to generate a detected bandwidth signal, and a mode control circuit configured to control a mode of the envelope tracker based on the detected bandwidth signal, the mode control circuit further configured to disable the error amplifier when the detected bandwidth signal indicates that a bandwidth of the radio frequency signal is less than a first threshold.

A method of automatic mode control in an envelope tracking system, the method comprising:

• amplifying a radio frequency signal using a power amplifier;
• powering the power amplifier with a power amplifier supply voltage from an envelope tracker;
• detecting a signal bandwidth of the radio frequency signal based on processing an envelope signal using a signal bandwidth detection circuit of the envelope tracker, the envelope signal corresponding to an envelope of the radio frequency signal;
• controlling a mode of the envelope tracker based on the detected signal bandwidth using a mode control circuit of the envelope tracker;
• and
• disabling an error amplifier when the detected signal bandwidth is less than a first threshold, and operating a DC-to-DC converter and the error amplifier in parallel with one another to generate the power amplifier supply voltage when the detected signal bandwidth is greater than a second threshold.