Yuqi Liu

Last Name

Liu

First Name

Yuqi

ORCID

0000-0002-7968-0074

Organisational unit

09757 - Wang, Hua / Wang, Hua

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Publications 1 - 10 of 25

AI-Assisted Template-Seeded Pixelated Design for Multi-Metal-Layer High-Coupling EM Structures: A Ku-Band 6G FR3 PA in 22nm FDX+
Chu, Chenhao; Xu, Jinglong; Liu, Yuqi; et al. (2025)
A Joint Space/Time Modulation Lens-Coupled 230-GHz Terahertz Source with 40°/43°2-D Beam Steering for Fast High-Resolution Imaging/Sensing Applications
Jalili, Hossein; Liu, Yuqi; Huang, Tzu-Yuan; et al. (2022)
ESSCIRC 2022- IEEE 48th European Solid State Circuits Conference (ESSCIRC)
This paper presents an integrated reconfigurable terahertz source array which employs a new method of joint space/time modulation to perform 2-D scalable and wide-range beam steering without phase shifters in a lens-coupled radiation set up. The reconfigurable array circuit can he activated in a variety of ways and is capable of simultaneous multi-beam/-frequency radiation. The chip is implemented in a 22nm CMOS-SOI process with a total area of 2.3 x 2.3mm(2), consumes 21-62.5 mW power per cell from a 0.8 V supply voltage, and provides a total of 40°/43° 2-D scanning range at 230-GHz frequency.
A 0.5W <3dB IL DC-67GHz SPDT Switch in 16nm FinFET with Local Substrate Floating Technique
Liu, Yuqi; Wang, Hua (2024)
19th European Microwave Integrated Circuits Conference (EuMIC 2024)
This paper presents a low-loss broadband SPDT T/R switch with <3dB insertion loss, >22dB isolation, and half-watt input 1dB compression point at 28GHz in TSMC 16nm FinFET process. By floating the local substrate in the vicinity of the switch device, loss and parasitic reduction can be achieved due to increased shunt impedance in the substrate network. It also helps provide more balanced voltage swing division within stacked transistors. Together with the introduced voltage swing on the deep-n-well to p-substrate diode, significant improvement in large-signal linearity is observed at mm-Wave. The measured prototype achieves DC to 67GHz operation with its performance at 28GHz as 1.86dB insertion loss, 29.4dB isolation, and 27.5dBm input 1dB compression point using only three stacked devices. To the best of our knowledge, this is the first reported mm-Wave SPDT switch using TSMC 16nm FinFET process.
MHz-to-THz Plasmonic Modulator
Moor, David; Horst, Yannik Matthias Julius; Chelladurai, Daniel; et al. (2024)
2024 IEEE Photonics Conference (IPC)
Plasmonic modulators are demonstrated to feature a THz bandwidth. Characterizations from 10 MHz to beyond 1 THz are performed. The modulator and pad capacitances are extracted and quantified, indicating potential for even higher bandwidths. We demonstrate the fastest electro-optic component to date.
A DC-50GHz DPDT Switch with > 27dBm IP1dB in 45nm CMOS SOI
Liu, Yuqi; Park, Jeongsoo; Wang, Hua (2022)
2022 IEEE/MTT-S International Microwave Symposium - IMS 2022
This paper presents a DPDT T/R switch in a 45nm CMOS SOI process. The switch employs shunt-series-shunt topology with thin-oxide transistor having low on-resistance in the series branch to provide low insertion loss and thick-oxide transistor having higher threshold and breakdown voltage in the shunt branch to offer high linearity. Together with resistive stacking of transistors and negative biasing schemes for further linearity and isolation enhancement, the proposed design achieves broadband operation from DC to 50GHz, with <3dB IL, >22dB isolation with power handling capability greater than half a watt.
Fully integrated topological electronics
Liu, Yuqi; Cao, Weidong; Chen, Weijian; et al. (2022)
Scientific Reports
Topological insulators (TIs) have attracted significant attention in photonics and acoustics due to their unique physical properties and promising applications. Electronics has recently emerged as an exciting arena to study various topological phenomena because of its advantages in building complex topological structures. Here, we explore TIs on an integrated circuit (IC) platform with a standard complementary metal-oxide-semiconductor technology. Based on the Su-Schrieffer-Heeger model, we design a fully integrated topological circuit chain using multiple capacitively-coupled inductor-capacitor resonators. We perform comprehensive post-layout simulations on its physical layout to observe and evaluate the salient topological features. Our results demonstrate the existence of the topological edge state and the remarkable robustness of the edge state against various defects. Our work shows the feasibility and promise of studying TIs with IC technology, paving the way for future explorations of large-scale topological electronics on the scalable IC platform.
Analysis and Design of Differential Complex Neutralization Power Amplifiers for Efficient-Yet-Linear High Mm-Wave Applications
Eleraky, Mohamed; Huang, Tzu-Yuan; Liu, Yuqi; et al. (2024)
2024 IEEE/MTT-S International Microwave Symposium - IMS 2024
This paper presents a systematic design and optimization methodology to enhance the power gain of a given device towards its theoretically maximum stable power gain 4U, U as the Mason's Unilateral power gain, over a wide bandwidth. A device-level Gain-Bandwidth product (GBW) metric is also defined to assess high mm-Wave device gain boosting. The proposed technique exploits a high-order complex neutralization embedding network on a differential power device pair. For proof-of-concept, a D-band 3-stage PA with two-way power combining is implemented in GlobalFoundries 45 nm SOI process. The measurements show a peak power gain of 21.7 dB with a 3-dB BW of 15 GHz (117-132 GHz) in a compact area of 0.116 mm(2). The wideband device gain enhancement allows the PA to operate in class-AB biasing, achieving efficient-yet-linear operations at 127.5 GHz with P-sat and OP1dB of 11.9 and 11.85 dBm respectively and a peak PAE of 15%.
Design and Analysis of Complex Neutralization Gain-Boosting Technique With Low-Loss Power Combining for Efficient, Linear D-Band Power Amplifiers
Eleraky, Mohamed; Huang, Tzu-Yuan; Liu, Yuqi; et al. (2025)
IEEE Transactions on Microwave Theory and Techniques
This article introduces a comprehensive design and optimization approach aimed at significantly improving the power gain of a given device to achieve the theoretical maximum stable power gain, denoted as 4U (with U representing Mason’s Unilateral power gain), across a wide bandwidth. To evaluate the wideband gain enhancement of the device, a device-level Gain-Bandwidth Product ( GBW ) metric is presented. The proposed technique leverages a high-order embedding network, specifically complex neutralization, applied to a differential power device pair. The detailed optimization process is presented alongside theoretical modeling. To address the limited output power at the D-band, a highly efficient power-combining network is co-designed with the output-matching network of the power amplifier (PA). To validate the proposed methodology, a D-band three-stage PA with two-way power combining was implemented using the GlobalFoundries 45-nm SOI process. The amplifier occupies a compact active area of 0.116 mm². Small-signal measurements demonstrate a peak power gain of 21.7-and a 3-dB bandwidth (BW) of 15 GHz, covering the frequency range from 117 to 132 GHz. The enhanced power gain enables the PA drivers to operate efficiently and linearly in class-AB biasing mode at 127.5 GHz, delivering a saturated output power ( P_sat ) of 11.9 dBm, output power at 1 dB compression point ( OP_1dB ) of 11.85 dBm, and a peak power-added efficiency (PAE) of 15%. This allows the PA to achieve an average output power of 7.1 (5.9) dBm under 64-QAM (128-QAM) modulation with a data rate of 27 (16.8) Gb/s. The PA shows an average modulation efficiency of 6.9% (5.15%) with an rms error vector magnitude ( EVM_rms ) better than − 24.8 ( − 25.7) dB.
A Wideband Bi-Directional Calibration-Free Frequency/Switching-Staggering 360° D-Band Phase Shifter with Frequency-Invariant Codes Achieving < 2.38°/0.63dB RMS-Errors Over 24% Bandwidth
Abdelmagid, Basem Abdelaziz; Liu, Yuqi; Wang, Hua (2025)
2025 IEEE International Solid-State Circuits Conference (ISSCC)
With the increasing need for high data-rate and channel throughput, the D-band (110 to 170GHz) has been actively explored for beyond-5G and 6G wireless communication, sensing, and radar applications [1], [2]. To overcome the severe free-space path loss at D-band, large-scale phased arrays are essential to focus and steer the radiation beams [3]–[5]. As summarized in Fig. 33.4.1 (top), D-band phased arrays come with a list of system challenges, which affects the design requirements of the front-end building blocks, in particular the phase shifters (PSs). First, the array element should fit into a ∼λ/2×λ/2 grid dictated by the antenna spacing (1mm×1mm at 150GHz). This requires compact PSs with a desired bidirectional ability to enable PS sharing between a transmitter and receiver of each element. Second, due to the narrow beamwidth of large-scale phased arrays, accurate beamforming is essential, requiring PSs with 360∘ phase range, accurate phase control (low rms phase error), and sufficiently fine resolution (~4 to 6b). Third, to simplify the phase/gain calibration of the array elements for fast beam forming/steering, PSs with minimum gain variations across phase states (low rms gain error) and phase codes independent of frequency are highly desirable. Fourth, with the compact element area of D-band arrays, low element-level power consumption is necessary to lower thermal density. This either requires active PSs with low DC power or zero-power passive PSs with low insertion loss (IL). Finally, supporting large data-rates demands wideband front-ends, requiring PSs that can achieve all the aforementioned desirable features across wide bandwidths.
Monolithically Integrated Optical Phased Array for Optical Wireless Communication
Kim, Youngin; Kulmer, Laurenz; Keller, Killian; et al. (2024)
Journal of Lightwave Technology
This paper presents a compact and power efficient one-chip optical phased array (OPA) transmitter (TX) for optical wireless communication (OWC). A traveling-wave-electrode Mach-Zehnder modulator (TWE-MZM) and mm-Wave driver, which would traditionally be implemented by bulky off-the-shelf components, are monolithically integrated with a silicon-based 1×64 OPA onto a single chip, reducing an active area of the entire system down to 6.4 mm 2 . Moreover, a co-design and integration of TWE-MZM and mm-Wave driver largely minimizes the parasitics and mismatches of an interface between the TWE and mm-Wave driver. The 64-element optical antenna achieves beam divergence of 0.77˚ and 4.23˚ over transversal and longitudinal direction, respectively. The two-sided beam-steering angles of the array antenna in transversal and longitudinal direction are ±14.3˚ and 6.1˚, respectively, while the side-lobe suppression ratio is 7.81 dB. The co-integrated TWE-MZM and driver support a measured data rate up to 15 Gbps and consume 210 mW. To the best of our knowledge, our proposed electronic-photonic integrated circuit is the first OWC-application OPA TX, which monolithically integrates TWE-MZM, CMOS driver, and OPA all in one-chip.

Publications 1 - 10 of 25

Yuqi Liu

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