Power detector

An apparatus, comprising:

• a resistive element including a first terminal and a second terminal, wherein the resistive element is coupled between a power amplifier and an antenna;
• a first squaring circuit including an input and an output, wherein the input of the first squaring circuit is coupled to the first terminal of the resistive element;
• a second squaring circuit including an input and an output, wherein the input of the second squaring circuit is coupled to the second terminal of the resistive element;
• a transformer, wherein the transformer comprises:
• a first inductor coupled between the first terminal of the resistive element and the second terminal of the resistive element;
• and
• a second inductor coupled between the input of the first squaring circuit and the input of the second squaring circuit, wherein the second inductor is magnetically coupled with the first inductor;
• and
• a difference circuit coupled to the output of the first squaring circuit and the output of the second squaring circuit.

A method for measuring power using a resistive element coupled between a power amplifier and an antenna, the method comprising:

• squaring a voltage from a first terminal of the resistive element to obtain a first signal;
• squaring a voltage from a second terminal of the resistive element to obtain a second signal;
• inputting the first signal to a first input of a differential amplifier;
• inputting the second signal to a second input of the differential amplifier;
• and
• obtaining a measurement signal at an output of the differential amplifier.