High Performance S-Band GaN T/R Module Using Hybrid Microwave Integrated Circuit

This article presents a comprehensive design framework and realization approach for a state-of-the-art, compact, ultra-lightweight, highly efficient, cost-effective S-band gallium-nitride (GaN) dual transmit/receive (T/R) module. The T/R module design considers the behavioral model of commercial off-the-shelf (COTS) microwave monolithic integrated circuits (MMIC), insertion characteristics of passive components, and microwave traces. A field programmable gate array (FPGA) based controller board generates the required T/R module controls, timing signals, and DC voltage bias sequencing for the various components. A thermal equivalent circuit model uses thermal conductivity and MMIC/passive components’ heat dissipation to determine the thermal margin for the safe operation of the devices. The thermal analysis determines the most critical competent of the T/R module and cooling mechanism for safe operation. The T/R module is realized using multilayer digital and microwave printed circuit board (PCB) technology and leverages advanced surface mount technology (SMT) manufacturing for low-cost volume production with high repeatability and reliability. In the presented design, two T/R modules are housed in a single thermally efficient Aluminium 6061-T6 enclosure, allowing the sharing of power and control circuits between the two modules to achieve the compact shape and size of the module. The T/R module is realized and evaluated for transmit and receive parameters, i.e., output power, receiver gain, noise figure, power consumption heat dissipation, power added efficiency, band-pass filter response, attenuator and phase shifter error, pulse width, duty cycle, and control timing parameters. The measured results of the T/R module are compared with state-of-the-art T/R modules available in open literature, matching or exceeding the performance. A passive golden reference unit (GRU) is used for mass production of factory-calibrated (phase-matched) T/R modules, which eliminates the requirement of periodic field calibration of the active phased array antenna (assuming uniform aging and environmental factors for produced T/R modules).