< BK21+ BEST Seminar Series Announcement> 

Time and Date : 10:00 ~ 12:00 Friday 11/23/2018

Place : D408, Engineering Building #4

Title : Advanced Integrated Power Conversion: From High-power to RF Systems

Abstract:

Circuits and architectures for efficient power conversion have become crucial in emerging

smart systems. Switching power amplifiers (PA) are very attractive for such applications, because

they exhibit better efficiency compared to linear PA designs, due to saturated operation. Switching PAs also allow for utilization of deep submicron CMOS technologies, due to which these designs can be easily integrated with digital circuits, and can benefit from process scaling, in performance as well as in area.

Pulse-width-modulation (PWM) is commonly used with switching PAs. A PWM signal typically

employs a high-frequency switching pulse waveform as a carrier signal, wherein the pulse-width or duty-cycle of each pulse is modulated by a given low-frequency input signal. The carrier frequency can vary from several kHz to GHz, and is typically determined by the target application.

In this talk, advanced control for efficient power conversion circuits that use PWM from high-power to RF applications will be presented. I will present a digitally-intensive transmitter using RF-PWM with carrier-switching in the first part of the presentation. Proposed carrier switching concept not only allows the transmitter to drive modulated signals with large peak-to-average power ratio (PAPR), but also improves the back-off efficiency. The second part of the presentation, I will present a high-speed PWM driver with multi-level class-D PA. Employing a PLL-based PWM architecture enables high switching frequency operation with high linearity and a multi-level output stage provides high efficiency, at high switching frequency by reducing the switching levels. The final part of the presentation, I will present an efficient buck/buck-boost reconfigurable LED driver that supports PWM and pulse-frequency-modulation (PFM) operation. Power factor (PF) and total harmonic distortion (THD) are improved by employing proposed adequate reference control.

Presenter: Kunhee Cho, Senior Engineer / Qualcomm, Santa Clara, CA, USA

Host: Prof. Chae, Youngcheol, Yonsei EEE