Apparatus and methods to protect power amplifiers

An apparatus comprising:

• power amplifier circuitry having an input;
• digital-to-analog converter circuitry having an output coupled to the input of the power amplifier circuitry, and having an input;
• multiplier circuitry having an output coupled to the input of the digital-to-analog converter circuitry, and having a first input and a second input;
• first combiner circuitry having an output coupled to the first input of the multiplier circuitry, and having a first input and a second input;
• first mixer circuitry having an output coupled to the first input of the first combiner circuitry, and having an input;
• second mixer circuitry having an output coupled to the second input of the first combiner circuitry, and having an input;
• first interpolation circuitry having an output coupled to the input of the first mixer circuitry, and having an input;
• second interpolation circuitry having an output coupled to the input of the second mixer circuitry, and having an input;
• first frequency band envelope determination circuitry having an input coupled to the first interpolation circuitry, and having an output;
• second frequency band envelope determination circuitry having an input coupled to the second interpolation circuitry, and having an output;
• second combiner circuitry having a first input coupled to the output of the first frequency band envelope determination circuitry and a second input coupled to the output of the second frequency band envelope determination circuitry, and having an output;
• and
• signal monitor circuitry having an input coupled to the output of the second combiner circuitry.

An apparatus comprising:

• frequency band envelope determination circuitry configured to determine an envelope corresponding to a first band signal, and having an output;
• combiner circuitry having an input coupled to the output of the frequency band envelope determination circuitry and configured to generate a combined envelope signal by combining the envelope corresponding to the first band signal with an envelope corresponding to a second band signal, and having an output;
• signal monitor circuitry configured to determine that the combined envelope signal satisfies a damage criterion of a power amplifier, and having an output;
• controller circuitry having an input coupled to the output of the signal monitor circuitry and configured to generate a power reduction value, and having an output;
• and
• multiplier circuitry having a first input coupled to the output of the controller circuitry, the multiplier circuitry configured to reduce a power of a combined radio frequency (RF) signal based on the power reduction value, the combined RF signal corresponding to the combined envelope signal.