A 4 Element Phased Array Transmitter with Efficiency Enhancement Using Beamforming for High-Bandwidth WLAN Applications

This paper presents a 4-element phased array transmitter with efficiency enhancement using beamforming for high bandwidths WLAN application. The efficiency enhancement is achieved by over-the-air combining technique and a sequential operation of the different chains. The signal peaks and the remaining data are transmitted through different RF chains, each optimized for a specific power, and recombined over the air to form the desired signal. A 5GHz PA with fast 2nsec on/off switching time was designed in 0.18µm CMOS process to demonstrate the efficiency boost technique. For the 4-element array configuration, efficiency enhancement of ×2.3 was demonstrated for 80MHz MSC9 802.11ac signals with 9dB peak-to-average-ratio and EVM of -32dB.