Abstract: A square law extension circuit is disclosed that operates over a range of frequencies and power levels. The square law extension circuit includes a detector, an amplifier, and an expander. The detector has an input for receiving radio frequency (RF) signals and providing a detected signal output. The amplifier has an input that receives the detected signal output of the detector and provides an output for an amplified detected signal. The expander has an input that receives the amplified detected signal and is arranged to provide an expanded signal output. The expanded signal output is a signal that increases in a first proportion to the amplified detected signal up to a predetermined threshold and increases at a second proportion to the amplified detected signal that is more than the first proportion when the expanded signal output exceeds the predetermined threshold.