Compact 4‐bit GaAs Ku‐band core chips for phased arrays

In this letter, we present an Rx core chip and a Tx core chip for Ku‐band phased arrays, which are designed and fabricated using the commercial 0.25‐μm GaAs pHEMT foundry service. Each of the Rx core chip and the Tx core chip has a 4‐bit phase shifter driven by an on‐chip serial‐to‐parallel (SPC) converter. The on‐chip SPC provides the serial interface with an external controller. The Rx core chip shows a gain >10 dB, a noise figure less than 2 dB at a frequency range of 10.7 to 12.75 GHz and for all phase states of the 4‐bit Rx phase shifter. The Tx core chip shows a gain >10 dB, an output P1dB of about 13 dBm at a frequency range of 13.5 to 15.5 GHz and for all phase states of the 4‐bit Tx phase shifter. The Rx core chip and the Tx core chip have the same size of 1.75 × 1.75 mm2, which we believe the state of the art size among the presented GaAs core chips.