Wireless: Non-volatile RF switches, efficient transmitter, time-division MIMO.
Researchers from Ulsan National Institute of Science and Technology (UNIST) designed non-volatile RF switches based on vanadium oxide (VOx) for high-frequency bands used in next-generation wireless communications like 6G.
The RF switch uses a memristor structure that enables it to operate and maintain its set state without consuming standby power. Additionally, the memristor’s resistance switching speed is on the order of a few nanoseconds, enabling rapid on/off switching and minimizing signal processing delays.
Experimental tests demonstrated that the device can handle high-frequency signals up to 67 GHz, maintaining low insertion loss (below 0.46 dB) in the ON state and high isolation (above 20 dB) in the OFF state. Simulations indicated that the device could operate at frequencies up to 4.5 THz. The team used the RF switch in a tunable bandpass filter that allows the center frequency to be adjusted within a range of approximately 600 MHz. [1]
Researchers from the Massachusetts Institute of Technology (MIT), Boston University, and Northeastern University designed a transmitter chip that improves the energy efficiency of wireless communications.
The chip employs a unique modulation scheme to encode digital data into a wireless signal. The transmitter adds a small amount of padding, in the form of extra bits between symbols, so that every transmission is the same length, helping the receiver identify the beginning and end of each transmission and reduce errors. The device also receives the energy efficiency gains of using a non-uniform, optimal modulation scheme.
The transmitter uses an approach inspired by a universal decoding algorithm previously developed by the team that can decode by guessing the noise that affected the transmission. The algorithm is used to adjust the length of the received transmission by guessing the extra bits that have been added, enabling the receiver to reconstruct the original message.
The architecture allowed the researchers to integrate additional efficiency-boosting methods, enabling transmissions with only about one-quarter the amount of signal error of methods that use optimal modulation. [2]
Researchers from the Institute of Science Tokyo proposed a time-division Multiple-Input Multiple-Output (MIMO) technology for 6G low-earth orbit satellites that enables phased-array receivers to operate faster than conventional systems with high area efficiency and low power.
Instead of relying on spatial multiplexing, the design reuses the signal paths for different streams through fast, random switching. The team’s non-uniform time-hopping approach achieves high-speed beam switching within the phased-array antenna module without the need to scale the circuit according to the number of MIMO streams.
The researchers implemented a receiver using a 65nm silicon CMOS process and incorporated high-speed switching phase shifters to improve resistance to interference. The system integrates eight signal paths with synchronized switches and operates at a clock frequency of 3.2 GHz. Through over-the-air measurements, the receiver achieved 4×4 MIMO signal reception for both horizontal and vertical polarizations, delivering a maximum data rate of 38.4 Gbps across eight streams. [3]
[1] D. Seo, D. Kim, J. Ryu, et al. VOx-Based Non-Volatile Radio-Frequency Switches for Reconfigurable Filter. Adv. Sci. 2025, e01989. https://doi.org/10.1002/advs.202501989
[2] T. Zirtiloglu, A. Tan, B. Ozaydin, et al. “A Fully Integrated Optimal Modulation Bits-to-RF Digital Transmitter using Time-Interleaved Multi-Subharmonic-Switching DPA,” 2025 IEEE Radio Frequency Integrated Circuits Symposium (RFIC), San Francisco, CA, USA, 2025, pp. 15-18, http://dx.doi.org/10.1109/RFIC61188.2025.11082855
[3] M. Tang, Y. Zhang, D. Xu, et al. A Ka-Band 8-Stream Phased-Array Receiver with Time-Hopping Blocker Rejection for 6G Applications. Technical digest of the 2025 Symposium on VLSI Technology and Circuits. https://doi.org/10.23919/VLSITechnologyandCir65189.2025.11074812
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