InGaP/GaAs WLAN power amplifier with detector using on-chip coupler

This paper presents a power amplifier with an on-chip power detector for 2.4 GHz wireless local area network (WLAN) application. The power detector consists of a clamp circuit, a diode detector and a coupled line directional coupler. A series inductor for an output matching network in the power amplifier is combined with a through line of the coupler, which reduces the coupling level. Therefore, the coupler employs a metamaterial-based transformer configuration to increase coupling. The amount of coupling is increased by 2.5 dB in the 1:1 symmetric transformer structure and by 4.5 dB from 2 metamaterial units along the coupled line.