Aug 20 (Tue) @ 9:00am: "Millimeter-Wave Materials, Opto-Electronic Circuits, and High-Efficiency Power Amplifiers," Shu-Ming Chang, ECE PhD Defense

Abstract

This thesis explores three key areas:

1. Free-Space Dielectric Characterization of Diamond Composites:

With the increasing demand for compact millimeter-wave arrays, novel packaging solutions using low-cost dielectric materials with high thermal conductivity (∼100 W/m·K) are essential. To accurately measure the permittivity and loss tangent of these materials above 100 GHz, a free-space characterization method is proposed to eliminate the need for de-embedding conductor losses. This research reviews current characterization techniques and investigates the properties of ultra-dense diamond composite materials at D-band frequencies. By employing time-domain gating, we minimize uncertainty in the characterization process. Materials characterized include pure polymer TMPTA, PDMS, TMPTA-based, and PDMS-based diamond composites, as well as quartz and sapphire wafers for calibration from 120–160 GHz. This study presents the first known characterization of diamond composites for thermally conductive dielectric packaging requirements at D-band frequencies.

2. A Tapped Transmission Line Ring Power Amplifier for High Peak and Average Efficiency:

A novel tapped transmission line ring network is introduced, enabling simultaneous tuning of high-power (HP) and low-power (LP) power amplifiers (PAs) to optimize both peak and average efficiency. This passive network simultaneously matches each PA to its optimal load impedance for maximum power-added efficiency (PAE). Implemented in a 45-nm CMOS SOI process, the PA operates from 26-31 GHz with a 6-dB output backoff range. The HP mode achieves a saturated output power (Psat) of 19 dBm with 35.1% PAE, while the LP mode achieves a Psat of 15.2 dBm with 35.7% PAE.

3. Joint Radar and Lidar Receiver: Amplifier and Mixer Design:

This work presents a converged radar and lidar receiver array that offers improved sensing robustness over individual sensors. A D-band joint low-noise amplifier (LNA) and transimpedance amplifier (TIA) are designed to amplify both millimeter-wave radar and optical lidar signals using the same NMOS transistors. Additionally, a down-conversion mixer is developed for a direct-conversion receiver, enabling the down-conversion of RF signals to baseband using optically driven local oscillator (LO) signals.

Bio

Shu-Ming Chang received B.S. degree in Engineering Science from National Cheng Kung University, M.S. degree in electrical engineering from National Taiwan University. He worked at Taiwan Semiconductor Manufacturer Company (TSMC) from 2013 to 2019 as a spice modeling engineer. Currently, he is pursuing Ph.D. in ECE at UCSB since 2019. He focuses on millimeter-wave circuit design and free-space material characterization.

Hosted by: Professor James Buckwalter

Submitted by: Shu-Ming Chang <shu-ming@ucsb.edu>