PhD NEWS
New PhD Theses from Singapore
The School of Electrical and Electronic Engineering of Nanyang Technological University in Singapore has recently turned out two new PhDs. They are Dr Chong Kwen Siong and Dr Yongzhi Liu. Details of their works are as follows.
Dr Chong Kwen Siong’s thesis topic was Design and Implementation of a Low Energy Fast Fourier Transform / Inverse Fast Fourier Transform (FFT/IFFT) Processor Based on Asynchronous-Logic. The thesis advisor was Dr Gwee Bah Hwee. Dr Chong’s thesis pertains to circuit designs using the emerging asynchronous-logic (async) approach as opposed to the prevalent synchronous-logic (sync) approach, with emphases on low voltage operation and low energy dissipation. The circuits designed herein span from microcells and macrocells to a complete 128-point radix-2 decimation-in-time Fast Fourier Transform/Inverse Fast Fourier Transform (FFT/IFFT) processor for energy-critical audio applications, including hearing aids. The novel microcells and macrocells include a Latch Adder, a Latch Accumulator, a Type- 2-bit carry completion sensing adder, a latch controller, a 16×16-bit Booth array-based multiplier core, a 16×16-bit ‘Control-Multiplier’, and a 128×16-bit memory macrocell. The novelties of these designs include the incorporation of different functional features and reduced spurious switching, resulting in increased versatility, compactness, and lower energy dissipation. By means of appropriate async design techniques and proposed microcells and macrocells, the async FFT/IFFT processor is demonstrated to feature superior energy attributes over its sync counterpart.
Dr Yongzhi Liu’s thesis topic was Design of Finite Impulse Response Filters with Reduced Group Delays and Active/Robust Array Beamformers. The thesis advisor was Dr Zhiping Lin. Dr Liu’s thesis presents research work on two related topics, namely, finite impulse response (FIR) filter design and array beamforming. The focus is on the design of FIR filters with reduced passband group delay errors and efficient/robust array beamforming algorithms. The thesis consists of two parts. In the first part, to effectively reduce the group delay error in filter design, group delays of simple FIR filters and frequency response masking (FRM) FIR filters are analyzed and an explicit group delay constraint is incorporated into the problem formulation, which is then cast into the convex programming framework. In the second part, by adopting the FRM FIR filter weights as aperture functions in active array beamforming, beampatterns with sharp transition are synthesized which use fewer sensors than conventional methods with similar beampatterns. To improve the robustness of beamformers against direction of arrival (DOA) mismatches, a class of leakage constraints is derived and exploited in the design of general sidelobe cancellers (GSC).
IEEE CAS Singapore Chapter
