Millimeter-wave (mmWave) power amplifiers (PAs) are critical building blocks in next-generation radar, satellite, defense, and 6G communication systems, where output power, bandwidth, and efficiency must be achieved under stringent size, weight, and power (SWaP) constraints. Among the enabling technologies, Gallium Arsenide (GaAs) and Gallium Nitride (GaN) continue to dominate due to their complementary strengths in linearity, noise performance, and high-power density. This talk will focus on design considerations unique to mmWave GaAs and GaN PAs, with particular emphasis on stability and biasing challenges at frequencies above 20 GHz. Unlike lower microwave designs, mmWave PAs are highly susceptible to low-frequency oscillations, odd-mode instabilities, and bias-induced resonances. To mitigate these, stability networks—ranging from RC shunt loading and resistive feedback to series loading and quarter-wave stabilization—must be co-optimized with matching and biasing schemes. Special attention will be given to the integration of stability networks with bias networks, where parasitics from bias chokes, decoupling capacitors, and high-impedance bias lines can introduce additional poles/zeros in the response, affecting both gain flatness and unconditional stability. The presentation will review practical approaches to stabilizing mmWave PAs without compromising efficiency or bandwidth, including the use of lossy transmission lines, broadband bias tees, and RC filtering strategies tailored for GaAs vs. GaN processes. Case studies will illustrate how bias network design impacts stability margins and overall PA performance, and how distributed versus lumped stabilization choices evolve with frequency. The session will conclude with a discussion of packaging and integration considerations, where bondwire inductances, via transitions, and LTCC/SiP bias routing play a defining role in amplifier stability at mmWave frequencies. Speaker(s): Asmita Dani, Room: 4021, Bldg: Sobrato Campus for Discovery and Innovation, Santa Clara University, 500 El Camino Real, Santa Clara, California, United States, 95054, Virtual: https://events.vtools.ieee.org/m/505939

With the rapid development of Internet of Things, a vast number of small, low-cost, and low-power mobile electronic devices, such as radio frequency identification tags and wireless sensors, will become integral parts of our society in the near future. Supplying electrical power to these devices wirelessly would eliminate/relieve their battery life limitation, and therefore is envisioned to be one of the enabling technologies for the next-generation Internet of Things. Since wireless power delivery must be dedicated to the designated receivers in space, it is inevitable to employ one narrow electromagnetic beam as the carrier of wireless power toward each mobile device. The retro-reflective beamforming technique has excellent potential to accomplish efficient wireless power transmission in the context of Internet of Things, as it is capable of keeping track of multiple mobile devices and then generating wireless power beams to the devices accordingly. The primary merit of retro-reflective beamforming technique is that wireless power transmission is augmented by radar tracking. Specifically, wireless power transmission is initiated by pilot signals broadcasted from wireless power receiver(s); and in response to the pilot signals, a wireless power transmitter delivers directional microwave power beams to the receiver(s). This presentation reviews our past, ongoing, and future research efforts on wireless power transmission based on retro-reflective beamforming. This talk starts with the fundamental principles and a brief history of retro-reflective beamforming technique. Next, the pros and cons of retro-reflective beamforming are analyzed via comparison with other wireless power transmission techniques. Plentiful theoretical and experimental results collected in our research demonstrate that the retro-reflective beamforming scheme enables microwave power beams to follow the location of mobile wireless power receiver(s) dynamically as long as the receiver(s) broadcast pilot signals periodically. The last part of the presentation discusses the challenges pertinent to the practical application of retro-reflective beamforming technique. Speaker(s): Mingyu Lu, Room: 4021, Bldg: Sobrato Campus for Discovery and Innovation, Santa Clara University, Santa Clara, California, United States, 95053

This presentation discusses high power monolithic microwave integrated circuit (MMIC) power amplifier (PA) design in Gallium Arsenide (GaAs) and Gallium Nitride (GaN). At a high level, GaN versus GaAs semiconductor technology from the perspective of power amplifier design metrics is analyzed to help determine the relative advantages and disadvantages of each technology. This is followed with an introduction of the most prevalent MMIC design topologies for the bulk of microwave applications which include reactively matched, non-uniform distributed, balanced, push-pull, Doherty and serially combined. Following introduction of the main topologies, the presentation focuses on the potential pitfalls the MMIC designer can encounter with detailed discussion on how to avoid them with the goal of first past design success. The presentation relies on experience from the author’s career with over 20 years of experience in the defense and commercial industries as well as academia. MMIC designers will appreciate the candid explanation of the design topologies and pitfalls while non-designers will come away with a good working knowledge of what can be achieved and what to watch out for. Speaker(s): , Michael Virtual: https://events.vtools.ieee.org/m/472102