Research Analog/Mixed-Signal ICs

Memristor-based RF Circuits

Adaptive radiofrequency integrated circuits (RFICs) are essential in wireless communication systems to effectively utilize the RF spectrum and meet the performance demands of modern mobile devices. As new standards such as 5G and millimeter wave (mmW) are introduced, more radios are being added to smartphones, requiring the use of adaptive RFICs for redundant hardware removal, resulting in a smaller area, lower complexity, and fewer modules in radio chips. The core of these systems is the RF switch, which controls the flow of the RF signal and provides tunable capabilities to different blocks.

Recently, resistive memory technologies such as RRAM, PCM, and CBRAM have emerged as strong candidates for RF switches due to their superior performance, small footprint, non-volatility, and compatibility with back-end-of-line fabrication [1]. These technologies achieve state-of-the-art cutoff frequency, making them great contenders for best-in-class RF switches. This research explores the novel capabilities of resistive memories for adaptive RF circuits. At the device level, we developed an in-house fabrication process for inline phase-change RF switches (IPCSs) using germanium telluride as the PCM [2], [3]. Our devices achieved state-of-the-art cutoff frequency while reducing the area and switching energy of RF switches. We also developed a physics-based compact model of the IPCS, which was experimentally validated through electrical thermometry, finite element method simulations, and RF measurements. This model enables rapid device optimization and the design and simulation of large-scale circuits composed of IPCS with varying substrates, dielectrics, and PCMs [3].

Furthermore, we explored the use of resistive memory technologies for tunable inductors and the fabrication process of tunable inductors based on the IPCS is being developed [4]. We also worked on the design and fabrication of several IPCS-based reconfigurable RF front-end blocks, such as multiplexers and phase-shifters, for the implementation of a multi-standard radio transceiver [5]. At the system level, we have explored the design spectrum to find the best system topology for a resistive memory-based reconfigurable radio [1].

Selected Papers

[1] N. Wainstein, E. Yalon, G. Adam, and S. Kvatinsky, “Radiofrequency Switches Based on Emerging Resistive Memory Technologies – A Survey”, Proceedings of the IEEE, Vol 109, No. 1, pp. 77-95, January 2021

[2] N. Wainstein, G. Ankonina, T. Swoboda, M. Muñoz Rojo, S. Kvatinsky, and E. Yalon, “Indirectly Heated Switch as a Platform for Nanosecond Probing of Phase Transition Properties in Chalcogenides”, IEEE Transactions on Electron Devices, Vol. 68, Issue 3, pp. 1298-1303, March 2021

[3] N. Wainstein ,G. Ankonina, S. Kvatinsky, and E. Yalon, “Compact Modeling and Electro-Thermal Measurements of Indirectly-Heated Phase Change RF Switches”, IEEE Transactions on Electron Devices, Vol. 67, Issue 11, pp. 5182-5187, November 2020

[4] N. Wainstein and S. Kvatinsky, “TIME – Tunable Inductors using MEmristors”, IEEE Transactions on Circuits and Systems I: Regular Papers, Vol. 65, No. 5, pp. 1505-1515, May 2018

[5] N. Wainstein and S. Kvatinsky, “A Lumped RF Model for Nanoscale Memristive Devices and Non-Volatile Single-Pole Double-Throw Switches”, IEEE Transactions on Nanotechnology, vol. 17, no. 5, pp. 873-883, September 2018

Memristor-based Analog Circuits

Memristors and new emerging nano-devices can be used in analog circuits as programmable resistors or switches to build tunable amplifiers, filters and AGC (automatic gain control) amplifiers for high dynamic range electronics.

All signal acquisition electronics have limited dynamic range. The lowest signal that can be acquired is limited by the analog electronic noise. Having amplifiers with high gain is beneficial in order to reduce the total noise, but such amplifiers can be easily saturated or damaged when exposed to high level signals, thus the dynamic range of the circuit is very limited.

Using memristors in such systems, would allow us to build new circuits that have a very high dynamic range, that is possible today only with very complex and power consuming circuits.

Our work is focused on using memristor and other new nano-devices to improve and create new analog circuits for high dynamic range signal acquisition circuits, tunable analog circuits and analog computing.