Overcoming Common Planar Phased Array Circuit Design Challenges

This article details the design and layout challenges associated with the  electronic design of planar phased arrays and focuses on an RF front end containing power amplifiers (PAs), low noise amplifiers (LNAs), and beamformers. It discusses the signaling and timing involved with control of PA and LNA biasing, transmit and receive switching, memory loading, and beam advance.The PCB layout discussion highlights a single cell, consisting of a beamformer surrounded by four transmit/receive (TR) modules. Thermal management challenges are discussed, including component side heat sinking and heat sink cavity design with RF absorbers to avoid oscillations. The power management design for the RF front end is explained, including the power tree and the specific bias sequencing required to avoid PA damage.