The Design of a Plastic Packaged Front-end IC for mmWave 5G

The presentation will start by reviewing semiconductor technology choices and SMT packaging options for mmWave ICs. It will then describe the development of a front-end mmWave IC containing LNA, PA, RF power detector, transmit/receive switch and associated control logic. The IC was designed for 28GHz (27.5 to 28.35GHz) time division duplex (TDD) 5G applications. It was developed on a 4V, 0.15µm enhancement mode GaAs pHEMT process and so only positive supply voltages are required. It has been packaged in a standard, low-cost 5mm x 5mm overmoulded plastic QFN package making it suitable for the high volume, low cost manufacturing. The transmit path was optimized for high efficiency when backed-off from compression to provide linear amplification and preserve modulation fidelity. When driven at 1dB gain compression it produces an output power of around 20dBm at a PAE of 20%. When backed off for linear operation, to an IMD3 point of -35dBc, the measured PAE is 6.5%. The receive path has a measured gain of 13.5dB with a noise figure of around 3.3dB from a supply current of just 10mA. The receive path also demonstrates impressive linearity of +20dBm IP3 for a modest power consumption of just 40mW. Details of the design approach, the IC layout and the incorporation of packaging parasitics to provide optimised performance of the packaged part on a representative PCB will be presented.