US Patent 8648661 Current limiting circuit

A current limiting circuit includes a power amplifier receiving an input signal through an attenuator. The power amplifier comprises one or more amplification stages and an output stage. The output stage is connected to an antenna. A mirror circuit is connected in parallel to the output stage. The magnitude of a first current flowing through the mirror circuit is proportional to the magnitude of a second current flowing through the output stage. Further, the current limiting circuit includes a comparator that compares the magnitude of the first current with a reference value to generate a control signal. The attenuator adjusts the power of the input signal based on the control signal thereby limiting the magnitude of the second current.