Sudipto Chakraborty

Abstract: This talk will cover principles and application of current mode design techniques for ultra low power transceivers/signal generators. Current mode design techniques are becoming popular in recent times due to emergence of beamforming and AI/ML applications. In this talk, a few novel constructs for current mode designs shall be presented that are implemented using 14nm CMOS FinFET technology for qubit state controller (QSC) used for next generation quantum computing applications. The QSC includes an augmented general-purpose digital processor that supports waveform generation and phase rotation operations combined with a low power current-mode single sideband upconversion I/Q mixer-based RF arbitrary waveform generator (AWG). Implemented in 14nm CMOS FinFET technology, the QSC generates control signals in its target 4.5GHz to 5.5 GHz frequency range, achieving an SFDR > 50dB for a signal bandwidth of 500MHz. With the controller operating in the 4K stage of a cryostat and connected to a transmon qubit in the cryostat’s millikelvin stage, measured transmon T1 and T2 coherence times were 75.7μs and 73μs, respectively, in each case comparable to results achieved using conventional room temperature controls. In further tests with transmons, a qubit-limited error rate of 7.76x10-4 per Clifford gate is achieved, again comparable to results achieved using room temperature controls. The QSC’s maximum RF output power is -18 dBm, and power dissipation per qubit under active control is 23mW.

Bio: Sudipto Chakraborty received his B. Tech from Indian Institute of Technology, Kharagpur in 1998 and Ph.D. in EE from Georgia Institute of Technology in 2002. He worked as a researcher in Georgia Electronic Design Center (GEDC) till 2004. Since 2004 to 2016, he was a senior member of technical staff at Texas Instruments where he contributed to low power integrated circuit design in more than 10 product families in the areas of automotive, wireless, medical and microcontrollers. Since 2017, he has been working at the IBM T. J. Watson Research Center where he leads the low power circuit design for next generation quantum computing applications using nano CMOS technology nodes. He has authored or co-authored more than 75 papers, two books and holds 76 US patents. He has served in the technical program committees of various conferences including CICC, RFIC, IMS and has been elected as an IBM master inventor in 2022 for his contributions.

Low-power Analog, RF Design Using Current Mode Techniques

Open Talk to all IEEE members sponsored by the Circuits and Systems Society under its Distinguished Lecturer Program

Carlos Galup

Abstract: Most SPICE models of bipolar transistors are based on the charge control relation proposed by Gummel in 1970. There are good reasons for that; in effect, the Gummel-Poon model is considered the most simple, elegant, and computational efficient compact model yet developed. The first charge-controlled model for MOS transistors was proposed by Maher and Mead in 1987; since then, several research groups have proposed different charge-based MOSFET models. In this keynote we will focus on the ACM2.0 model proposed last year, which has striking similarities with the Gummel-Poon core equations, the use of only five DC electrical parameters being one of them. The great advantage of the single-piece equation model of the ACM2.0, with a few but meaningful electrical parameters, is its usefulness not only for simulation, but also for properly sizing transistors in the pre-simulation phase of a design flow. Furthermore, jointly with the open-source PDKs and tools, simple and accurate compact models in open-source simulators also help the entrance of new engineers in the integrated circuit design domain.

Bio: Carlos Galup-Montoro (M’89, SM’17) studied Engineering Sciences at the University of the Republic, Montevideo, Uruguay, and Electronic Engineering at the National Polytechnic School of Grenoble (INPG), France. He received an Engineering degree in electronics in 1979 and a doctorate degree in 1982, both from INPG. From 1982 to 1989 he worked at the University of São Paulo, Brazil. Since 1990 he has been with the Department of Electrical and Electronics Engineering, Federal University of Santa Catarina, Florianópolis, Brazil, where he is currently a professor. In the second semester of the academic year 1997-1998 he was a research associate with the Analog Mixed Signal Group, Texas A&M University. He was a visiting scholar at UC Berkeley from 2008 to 2009 and at IMEP/INPG in the first trimester of 2017.

Charge-based transistor models facilitate the IC design process and the designer education