Publications by Hung-Chi Han | EPFL Graph Search

Self-heating Effects in RF Region of FDSOI MOSFETs at Cryogenic Temperatures

Christian Enz, Edoardo Charbon, Hung-Chi Han

Radio-frequency (RF) circuits are crucial to qubit manipulation, for which transistor self-heating effects may influence performance and possibly change the quantum state. This paper presents an analytical RF model of FDSOI MOSFETs considering dynamic self ...

Institute of Electrical and Electronics Engineers (IEEE)2025

Cryogenic sEKV Compact Model Applied to 22 NM FDSOI Enabling Low-Temperature Circuit Simulation

Christian Enz, Edoardo Charbon, Hung-Chi Han

IEEE2025

Cryogenic Circuit Performance Prediction Using Design-Oriented Model (SEKV) On 22nm FDSOI

Christian Enz, Edoardo Charbon, Hung-Chi Han

IEEE2025

Scaled-Footprint Ultra-Low Power Cryogenic InGaAs/InP HEMTs with Record-High Combination of Low-Noise and High-Frequency Performance

Kirsten Emilie Moselund, Edoardo Charbon, Hung-Chi Han

In this work we demonstrate cryogenic InxGa1-xAs/InP HEMTs with highly scaled gate footprints, down to 380 × 40 nm2 for a single gate finger, and investigate the impact of footprint scaling on device performance. The 80% In channel devices show fT=622 GHz ...

Institute of Electrical and Electronics Engineers Inc.2025

Modeling of the MOSFET for the Design of Cryo-CMOS Circuits

Christian Enz, Edoardo Charbon, Hung-Chi Han

This paper highlights some of the challenges faced in the modeling of MOSFET devices operating at cryogenic temperature (CT). It will review the most important phenomena, including the saturation of the subthreshold swing (S S) below a critical temperature ...

IEEE Computer Society2024

Cryogenic InGaAs HEMTs with Record-Low On-Resistance using Optimized Channel Structure

Edoardo Charbon, Hung-Chi Han

We present cryogenic InGaAs HEMTs showing record-low on-resistance and noise characteristics for low-power qubit readout. Our analysis focuses on transistors with different indium channel compositions, 70%, 75%, and 80%, to explain its impact on cryogenic ...

Institute of Electrical and Electronics Engineers Inc.2024

Analytical Modeling of Short-Channel MOSFET Differential Pair Non-Linearity

Christian Enz, Catherine Dehollain, Andreas Peter Burg, Hung-Chi Han

Energy efficiency is of utmost importance in modern applications. Power consumption optimisation could be improved by a comprehensive analytical modeling of the characteristics of critical blocks in a system. Dynamic range (DR) has a strong effect on the p ...

2024

Cryogenic Characterization and Modeling of Advanced MOSFET Technologies for Large-scale Quantum Computing

Hung-Chi Han

With the rapid advancement of quantum computing, there is a growing demand for reliable quantum devices operating at cryogenic temperatures to achieve fault-tolerant systems. Cryo-CMOS has recently gained much attention as the key solution to manipulating ...

EPFL2024

A Comprehensive Output Conductance Model Valid in All Regions of Inversion

Christian Enz, Hung-Chi Han

The output conductance and transconductance are key small-signal parameters that typically set the dc gain of amplifiers. Although the transconductance can be modelled simply and accurately, modeling the output conductance over a large range of bias and ge ...

IEEE2024

Analytical Modeling of Cryogenic Subthreshold Currents in 22-nm FDSOI Technology

Christian Enz, Edoardo Charbon, Hung-Chi Han

The transistor compact model is crucial but has yet to mature for cryogenic electronics. This paper presents a sophisticated analytical model of the MOSFET subthreshold current at cryogenic temperatures, accounting for the thermionic, hopping, source-to-dr ...

Institute of Electrical and Electronics Engineers2024

Design of Low-power Analog Circuits in Advanced Technology Nodes using the Gm/ID Approach

Christian Enz, Hung-Chi Han

The Gm/ID approach has proven to be an efficient technique for the design of low-power analog circuits. Until now it was mostly demonstrated on older CMOS technology nodes. In this paper we will show that the Gm/ID methodology still holds for advanced tech ...

IEEE2023

Design of Cryo-CMOS Analog Circuits using the Gm/ID Approach

Christian Enz, Hung-Chi Han

The Gm/ID approach has proven to be an efficient technique for the design of low-power analog circuits even in advanced technology nodes. It has already been shown that the normalized Gm/ID is actually a universal figure-of-merit (FoM) that is independent ...

IEEE2023

The Fano Noise Suppression Factor and the Gm/ID FoM

Christian Enz, Hung-Chi Han

This paper establishes the close relation that exists between the Fano noise suppression factor F and the Gm/ID FoM showing that F is proportional to the product of the thermal noise excess factor γn and the normalized Gm/ID function. Taking advantage of t ...

IEEE2023

Cryogenic InGaAs HEMTs with Reduced On-Resistance using Strained Ohmic Contacts

Christian Enz, Hung-Chi Han

We present InGaAs HEMTs with optimized cryogenic Ohmic contacts, for low-power qubit readout. We utilize tensile strained contact metals to reduce the barrier resistance, which is a major fraction of RSD, leading to ~50% reduction of RSD at low temperature ...

Institute of Electrical and Electronics Engineers Inc.2023

Analytical Modeling of Source-to-Drain Tunneling Current Down to Cryogenic Temperatures

Christian Enz, Hung-Chi Han

The subthreshold swing (SS) of MOSFETs decreases with temperature and then saturates below a critical temperature. Hopping conduction via the band tail has been proposed as the possible cause for the SS saturation. On the other hand, numerical simulations ...

Institute of Electrical and Electronics Engineers2023

An improved subthreshold swing expression accounting for back-gate bias in FDSOI FETs

Christian Enz, Farzan Jazaeri, Hung-Chi Han

In a MOSFET transistor, the subthreshold swing defines the switching efficiency, and the associated slope factor, or so-called body factor, is a critical parameter in charge-based models. However, in an advanced Fully -Depleted Silicon-On-Insulator (FDSOI) ...

PERGAMON-ELSEVIER SCIENCE LTD2023

SEKV-E: Parameter Extractor of Simplified EKV I-V Model for Low-Power Analog Circuits

Christian Enz, Hung-Chi Han, Antonio D'Amico

This paper presents the open-source Python-based parameter extractor (SEKV-E) for the simplified EKV (sEKV) model, which enables the modern low-power circuit designs with the inversion coefficient design methodology. The tool extracts the essential sEKV pa ...

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2022

Cryogenic InGaAs HEMT-Based Switches For Quantum Signal Routing

Christian Enz, Hung-Chi Han

We demonstrate cryogenic switching devices based on HEMT technology for scalable quantum computer (QC) control and readout signal routing. The switches are implemented in a quantum well network design without metal contacts between gates, and exhibit extre ...

IEEE2022

Back-gate effects on DC performance and carrier transport in 22 nm FDSOI technology down to cryogenic temperatures

Christian Enz, Edoardo Charbon, Farzan Jazaeri, Hung-Chi Han, Antonio D'Amico

This paper presents an in-depth DC characterization of a 22 nm FDSOI CMOS technology down to deep cryogenic temperature, i.e., 2.95 K. The impact of the back-gate voltage (V-back) on device performance, i.e., threshold voltage (V-T) and carrier transport, ...

PERGAMON-ELSEVIER SCIENCE LTD2022

Cryogenic RF Characterization and Simple Modeling of a 22 nm FDSOI Technology

Christian Enz, Edoardo Charbon, Farzan Jazaeri, Hung-Chi Han, Antonio D'Amico

This paper presents the RF characterization and modeling of a 22nm FDSOI technology down to 3.3K for quantum computing applications. The equivalent small-signal components are extracted analytically and automatically from the de-embedded two-port Y -parame ...

IEEE2022