@article{zhang_wang_li_dai_2012, title={Channel-aware adaptive resource allocation for multicast and unicast services in orthogonal frequency division multiplexing systems}, volume={6}, ISSN={["1751-8636"]}, DOI={10.1049/iet-com.2012.0111}, abstractNote={To support the multicast and unicast services in the orthogonal frequency division multiplexing system simultaneously, a channel-aware adaptive resource allocation algorithm is proposed to maximise the total throughput of the unicast service while guaranteeing the required quality of service (QoS) for the multicast service. The two-step optimisation scheme is developed to solve the problem based on the perfect channel state information at the base station: first, subcarriers are allocated to the multicast and the unicast services under the assumption that power is divided equally to every subcarrier. Especially, the noisy chaotic neural network with a new parameter set is applied to allocate the subcarriers to the unicast service by elaborately constructing the energy function to fully exploit the multiuser diversity gain, the optimal solution is found successfully through its rich neurodynamics; Secondy, the power averagely allocated to the unicast service is reallocated quickly in a linear water-filling fashion. Compared with existing algorithms the proposed algorithm achieves higher spectrum efficiency and better bit-error rate for the multicast service, also higher throughput for the unicast service.}, number={17}, journal={IET COMMUNICATIONS}, author={Zhang, H. and Wang, X. and Li, F. and Dai, H.}, year={2012}, month={Nov}, pages={3006–3014} }
 @inproceedings{wang_huang_2011, title={Capacitor energy variation based designer-side switching losses analysis for integrated synchronous buck converters in CMOS technology}, DOI={10.1109/apec.2011.5744736}, abstractNote={This paper introduces a designer-side switching loss analysis characterized by evaluating parasitic capacitor's energy variation and related losses for integrated synchronous Buck converters in CMOS technology (ISBC). After categorizing losses related to power FET parasitic capacitors' charging/discharging currents as charging/discharging losses (C_loss), it is noticed that the ratio of charging/discharging losses over capacitor's energy variation (ROCL) presents two extreme values; one of which is almost 100% and the other one is ignorable. Also, the same capacitor might encounter different ROCL when switching event is different. Five typical kinds of charging/discharging circuits are further classified in terms of ROCL. In order to evaluate parasitic capacitor's energy variation in a complete switching event, a hypothesis equation is adopted to cope with the variation of capacitance because of the operation mode shift of the power FET. At the same time, a process is introduced about how to verify the hypothesis and extract the unit width variables involved in the energy variation evaluation. The proposed switching losses analysis can provide losses breakdown in terms of semiconductor process technology data. At the same time, the analysis overcomes limitations in previous methods and supports the switching losses analysis for those advanced ISBC utilizing power stage width segmentation technology for the sake of wide load range efficiency. Transistor level simulation in Cadence environment verifies the analysis.}, booktitle={Annual ieee conference on applied power electronics conference and}, author={Wang, X. P. and Huang, A. Q.}, year={2011}, pages={1130–1137} }
 @inproceedings{wang_huang_2011, title={Considerations on the optimal power stage segmentation algorithm for MHz integrated synchronous Buck DC-DC converters}, DOI={10.1109/ispsd.2011.5890821}, abstractNote={For those MHz integrated synchronous Buck DC-DC converters (ISBC), a power stage segmentation technique might be applied for the sake of improving light load efficiency. The paper discusses the difference about efficiency in the case that losses contributions from Cds and Cgd in inactive power FET subcells are considered or not and indicates the existence of efficiency optimization's saturation effect in respect to the number of active power FET cells. After that, the paper presents the variation characteristics of power FET rdson using On-Semi SCN05 technology's eight manufacturing runs and temperature shift as two example cases. The variation of rdson implies that practical efficiency might deviate from an expected one, provided that the number of active power FET subcells is selected to be linearly proportional to the load current as that implemented in nowadays power FET width segmentation algorithms. Finally, the paper suggests a novel segmentation algorithm with automatic rdson compensation ability.}, booktitle={Proceedings of the international symposium on power semiconductor}, author={Wang, X. P. and Huang, A. Q.}, year={2011}, pages={184–187} }
 @article{wang_zhou_park_guo_huang_2010, title={Analysis of Process-Dependent Maximal Switching Frequency, Choke Effect, and Its Relaxed Solution in High-Resolution DPWM}, volume={25}, ISSN={["1941-0107"]}, DOI={10.1109/tpel.2009.2025272}, abstractNote={This letter uses the fanout-of-4 (FO4) metric to analyze the semiconductor process (SP) dependent maximal switching frequency (MSF) of a digital pulsewidth modulator (DPWM). After discussing the choke effect in a self-oscillating hybrid (SOH) DPWM and its impact on MSF, this letter further shows that separating the voltage-controlled oscillator (VCO) and the delay mux line is an effective way to relax the choke effect so that the MSF in the SOH could be almost doubled, together with 10%-20% power saving. Taking a low-cost AMI06 SP and 9-bit-resolution specification as an example, this letter predicts that 8 MHz switching frequency could be achieved with the proposed SOH. The SOH chip was custom-designed and fabricated in a 0.703 mm2 die via the metal oxide semiconductor implementation service (MOSIS) educational program. The chip test demonstrated that the MSF is 7.4 MHz with 1.07 mA power consumption, and the adjustable switching frequency range is from 1.8 to 7.4 MHz.}, number={1}, journal={IEEE TRANSACTIONS ON POWER ELECTRONICS}, author={Wang, Xiaopeng and Zhou, Xin and Park, Jinseok and Guo, Rong and Huang, Alex Q.}, year={2010}, month={Jan}, pages={152–157} }