In order to calibrate electrical instruments and generate a constant magnetic field, a novel design method for square Helmholtz coil is proposed. According to the superposition principle in electromagnetics, the theor...In order to calibrate electrical instruments and generate a constant magnetic field, a novel design method for square Helmholtz coil is proposed. According to the superposition principle in electromagnetics, the theory of the square Helmholtz coil is established, and the design method is verified by Matlab calculation. Compared with conventional circular Helmholtz coil, the novel square one is with a larger uniform region. Simulation work is conducted in Maxwell, and the distribution of the magnetic field is obtained. The results demonstrate the validation of the applied calculation method of the proposed Helmholtz model. The space utilization rate η is used to make a comparison between the square and circular coils for the uniform region. The square Helmholtz coil is fabricated, the length of a single square coil is 1.5 m, and the amplitude of the magnetic field is controlled by the current. The GSM-19 T proton magnetometer is used to measure the amplitude of the magnetic field generated by the square Helmholtz coil. Experimental results indicate that a wide-range variable uniform magnetic field from 0 to 120 μT is generated in the center of Helmholtz coils.展开更多
Intra-frame plays a significant role in improving video quality for rate control of H.264/AVC.In this paper,an efficient intra-frame rate control algorithm is proposed for H.264/AVC video coding.The proposed scheme ad...Intra-frame plays a significant role in improving video quality for rate control of H.264/AVC.In this paper,an efficient intra-frame rate control algorithm is proposed for H.264/AVC video coding.The proposed scheme adjusts the quantization parameter （QP） of intra-frame adaptively according to intra-frame buffer fullness ratio,current buffer fullness ratio,and skipped frame ratio.Experimental results demonstrate that for a set of typical testing sequences,the proposed scheme can obtain accurate target bit rate,better peak signal-to-noise ratio （PSNR） performance and reduce the number of skipped frames significantly,when compared with existing schemes.More importantly,the proposed scheme is very flexible for different initial QPs and target bits.展开更多
This paper presents the design of 0.5 V multi-gigahertz cascode CMOS LNA for low power wireless communication. By splitting the direct current through conventional cascode topology, the constraint of stacking- MOS str...This paper presents the design of 0.5 V multi-gigahertz cascode CMOS LNA for low power wireless communication. By splitting the direct current through conventional cascode topology, the constraint of stacking- MOS structure for supply voltage has been removed and based on forward-body-bias technology, the circuit can operate at 0.5 V supply voltage. Design details and RF characteristics have been investigated in this paper. To verify the investigation, a 0.5 V 5.4 GHz LNA has been fabricated through 0.18 μm CMOS technology and measured. Measured results show that it obtains 9.1 dB gain, 3 dB NF with 0.5 V voltage and 2.5 mW power dissipation. The measured IIP3 is -3.5 dBm. Compared with previously published cascode LNA, it achieves the lowest supply voltage and lowest power dissipation with competitive RF performances.展开更多
Analytical delay models for Resistance Inductance Capacitance(RLC)interconnects with ramp input are presented for different situations,which include overdamped,underdamped and critical response cases.The errors of del...Analytical delay models for Resistance Inductance Capacitance(RLC)interconnects with ramp input are presented for different situations,which include overdamped,underdamped and critical response cases.The errors of delay estimation using the analytical models proposed in this paper are less by 3%in comparison to the SPICE-computed delay.These models are meaningful for the delay analysis of actual circuits in which the input signal is ramp but not ideal step input.展开更多
基金The National Natural Science Foundation of China(No.61327803)
文摘In order to calibrate electrical instruments and generate a constant magnetic field, a novel design method for square Helmholtz coil is proposed. According to the superposition principle in electromagnetics, the theory of the square Helmholtz coil is established, and the design method is verified by Matlab calculation. Compared with conventional circular Helmholtz coil, the novel square one is with a larger uniform region. Simulation work is conducted in Maxwell, and the distribution of the magnetic field is obtained. The results demonstrate the validation of the applied calculation method of the proposed Helmholtz model. The space utilization rate η is used to make a comparison between the square and circular coils for the uniform region. The square Helmholtz coil is fabricated, the length of a single square coil is 1.5 m, and the amplitude of the magnetic field is controlled by the current. The GSM-19 T proton magnetometer is used to measure the amplitude of the magnetic field generated by the square Helmholtz coil. Experimental results indicate that a wide-range variable uniform magnetic field from 0 to 120 μT is generated in the center of Helmholtz coils.
基金Supported by the National Science Foundation for Creative Research Groups of China (60821062)
文摘Intra-frame plays a significant role in improving video quality for rate control of H.264/AVC.In this paper,an efficient intra-frame rate control algorithm is proposed for H.264/AVC video coding.The proposed scheme adjusts the quantization parameter （QP） of intra-frame adaptively according to intra-frame buffer fullness ratio,current buffer fullness ratio,and skipped frame ratio.Experimental results demonstrate that for a set of typical testing sequences,the proposed scheme can obtain accurate target bit rate,better peak signal-to-noise ratio （PSNR） performance and reduce the number of skipped frames significantly,when compared with existing schemes.More importantly,the proposed scheme is very flexible for different initial QPs and target bits.
基金Project Supported by the National Science Fund for Creative Research Groups of China(No.60821062)the National Basic Research Program of China(No.2009CB320202)
文摘This paper presents the design of 0.5 V multi-gigahertz cascode CMOS LNA for low power wireless communication. By splitting the direct current through conventional cascode topology, the constraint of stacking- MOS structure for supply voltage has been removed and based on forward-body-bias technology, the circuit can operate at 0.5 V supply voltage. Design details and RF characteristics have been investigated in this paper. To verify the investigation, a 0.5 V 5.4 GHz LNA has been fabricated through 0.18 μm CMOS technology and measured. Measured results show that it obtains 9.1 dB gain, 3 dB NF with 0.5 V voltage and 2.5 mW power dissipation. The measured IIP3 is -3.5 dBm. Compared with previously published cascode LNA, it achieves the lowest supply voltage and lowest power dissipation with competitive RF performances.
基金supported by National Science Fund for Creative Research Groups(No.60521002)the Grant of Doctoral Research Foundation from Ministry of Education,China(No.20040248034).
文摘Analytical delay models for Resistance Inductance Capacitance(RLC)interconnects with ramp input are presented for different situations,which include overdamped,underdamped and critical response cases.The errors of delay estimation using the analytical models proposed in this paper are less by 3%in comparison to the SPICE-computed delay.These models are meaningful for the delay analysis of actual circuits in which the input signal is ramp but not ideal step input.
