GaN Based Front-End MMIC for X-Band TR Modules

Abstract

Recent development in radars systems has shifted away the trend from mechanical dish antenna to multifunctional active electronically steered arrays (AESA). An AESA radar consists of an array of antenna elements each connected to a Transmit/Receive (T/R) module. Each T/R module consists of a phase shifter, digitally controlled attenuator, high power amplifier in transmit chain, switching circuitry and a low noise amplifier in receiver chain. Recent development in phased array systems require all of these components to be integrated on a single chip to provide a compact, reliable and cost effective T/R solution. Current T/R design trend focuses on two chip solution of T/R module which integrates core-ship with single chip front-end MMIC. High level integration of key front-end components, a Single Pole Double Throw (SPDT) T/R switch, High Power Amplifier (HPA) and Low Noise Amplifier (LNA), is required which can offer high output power in a small area. The integrated chip solution requires wideband operation and at the same time needs to offer low noise performance in the receiver chain. GaN Monolithic Microwave Integrated Circuit (MMIC) technology is being considered as an optimum solution which offers single chip integration of key front-end components of T/R modules for phased arrays in a small chip area. The design of GaN based front-end MMIC for T/R modules is an ideal solution to reduce size, weight, power and cost (SWAP-C) of T/R modules. The work on this thesis will focus on the design of 10 W fully integrated front-end MMIC for X-Band T/R modules. The designed MMIC will comprise of a SPDT T/R switch, HPA in the transmitter chain and a LNA in the receiver chain. The aim of this design is to achieve transmit and receive gain of > 15 dB with > 25 % transmitter efficiency and < 3.2 dB of receiver noise figure. Required isolation between transmitter and receiver chain is aimed to achieve > 25 dB. GaN technology is widely known for its robustness hence the possibility to omit limiter in the receiver chain will be tested. The integration of SPDT switch, LNA and HPA will provide a way to ease design complexity for a T/R module in AESA radars providing a two chip solution i.e. a core-chip along with a GaN front-end MMIC to make T/R module design compact, efficient and small.