Events

 
TRS-LED Seminar Series
TRS-LED Seminar Series

Titles & Speakers:
1. High Frequency, High Power Density DC-DC Converter by integrating GaN-on-Si & Embedded Coil
by Mr. Xing Lu

2. Above-CMOS Inductor (ACI) Integration Technique for Highly Integrated Power Management Systems
by Mr. Salahuddin Raju


Date
 :  14 Jun 2013 (Fri)
Time
 :  3pm - 4:30pm
Venue  :  ECE Conference Room 2512, 2/F (Lift 25/26), HKUST

Abstracts:
1) High Frequency, High Power Density DC-DC Converter by integrating GaN-on-Si & Embedded Coil
For power switching applications, there is a trend to increase the switching frequency in order to reduce the size of the converter design. In this perspective, GaN-based materials have attracted a lot of attention because of their outstanding properties such as high power density and high breakdown voltage. GaN HEMTs also show a low drain–source on-resistance and relatively small gate capacitances CGD and CGS. Moreover, GaN-based heterostructures can be grown onto large-diameter Si substrates, which is of course a major cost advantage.
In this talk, a novel on-chip DC-DC converter that features monolithically integrated GaN HEMT switches and embedded inductors will be proposed. The design consideration and process integration will be discussed in detail. Using standard GaN-on-Si epitaxial wafers, this integration concept takes advantage of high power, high switch speed GaN HEMTs and low power loss embedded coil in high resistivity Si substrate.
 
2) Above-CMOS Inductor (ACI) Integration Technique for Highly Integrated Power Management Systems
In power management applications, passive discrete components take more space than the CMOS control IC itself. Integration of these passives into the control IC could reduce the overall size, and most importantly it will reduce the total solution cost. One of the major passive discrete components in such application is the large valued inductor (~µH). On-chip integration of the large valued inductor is challenging and beyond the scope of conventional integration techniques. This work outlines a CMOS compatible on-chip inductor integration approach which can accommodate large valued inductors without affecting the area of active circuitry. In this methodology, inductor was fabricated above the passivation layer of the CMOS chip. Thick SU8 dielectric film (εr ≈ 2.8) was placed between the CMOS passivation layer and the inductor. SU8 film was also used to fabricate the inductor. SU8 can be easily patternable by photolithography, and after being cured by hard baking, it served the purpose of dielectric. In the process of inductor fabrication, SU8 was patterned to create deep trenches, and then these deep trenches filled with copper by damascene process. Since low-k dielectric material was placed beneath the inductor, the substrate loss was significantly reduced. Measurement results showed that the inductor quality factor can be achieve as large as 25 with inductance density of 200 nH/mm2. CMOS chip functionality also tested after integration to verify the process reliability. This integration approach will certainly facilitate fully integrated power management ICs which is essential in solid-state lighting applications. 

Bio:
Xing Lu received the B.S. degree in microelectronics from Fudan University, Shanghai, China, in 2010. He is currently pursuing the Ph.D. degree in electronic and computer engineering at The Hong Kong University of Science and Technology (HKUST).
He has been with the Photonics Technology Center and High Speed Silicon Laboratory, HKUST, since September 2010, under the supervision of Prof. K. M. Lau and Prof. C. P. Yue. His current research interests include design and implementation of the compound semiconductor MEMS and electronics.
 
Salahuddin Raju received the B.S. degree in electrical and electronic engineering from the Bangladesh University of Engineering & Technology (BUET). He is currently pursuing the MPhil degree in electronic and computer engineering at the Hong Kong University of Science and Technology (HKUST). His research interests include on-chip wireless power delivery interface design, and CMOS compatible 3-D passive integration.
 
 

Light refreshment will be served at the end of the seminar.
(The seminar is FREE while registration is needed. Please register HERE
)