电容降压直流电源的稳压设计

本文分析了电容降压直流电源的内阻和电压稳定系数，提出使用并联稳压器来改善电压稳定性，对并联稳压器的稳压特性作了分析计算，提出了自己的一些见解．

基于DSP的免损大电流开关电源研究

提出了一种基于DSP的免损大电流开关电源拓扑结构.开关电源的输入回路由串联电容及开关阵组成,输出回路由并联电容及开关阵组成,由运算速度快、计算精度高的DSP作为控制器,DSP输出可控脉冲,控制开关阵通断状态,以改变开关电源的输出.用状态平均法分析了开关电源充放电过程.对此开关电源做了计算机仿真实验,验证其输出电流可调特性.该开关电源具有输出电流可调、谐波小、体积小、损耗低的特点.

高性能跳频滤波器设计

提出了一种用无源谐振腔和有源电路相结合来实现高性能跳频滤波器的方法,利用开关电容阵加载腔体实现高速宽带低损的频率跳变。重点对这种跳频滤波器的插损和功率两个指标进行分析,包括腔体无载品质因数、PIN开关的功率和插损、加载射频电容的插损。利用三维电磁仿真软件HFSS和平面电路仿真软件ADS,结合具体的技术指标要求,给出了跳频滤波器部分电路的仿真曲线和测试结果。本滤波器具有高速、宽带、低损、体积小和数控的特点,因此可以广泛应用于跳频通信、软件无线电等领域。

A 2GHz Low Power Differentially Tuned CMOS Monolithic LC-VCO

A 2GHz differentially tuned CMOS monolithic LC-VCO is designed and fabricated in a 0.18μm CMOS process. The VCO has a 16.15% tuning range （from 1. 8998 to 2. 2335GHz） through a combination of analog and digital tuning techniques （4-bit binary switch-capacitor array）. The measured phase noise is - 118.17dBc/Hz at a 1MHz offset from a 2. 158GHz carrier. With the presented improved switch,the phase noise varies no more than 3dB at different digital control bits. The phase noise changes only by about 2dB in the tuning range because of the pn-junctions as the varactors. The VCO draws a current of about 2. lmA from a 1.8V power supply and works normally with a 1.5V power supply.

宇航SAR隔离型同步整流电源防电流倒灌方法

电流倒灌现象是同步整流电源中的常见问题,尤其对于输出端带大电容阵的宇航SAR隔离型同步整流电源而言,倒灌电流将严重影响其安全性、可靠性及使用寿命。提出了一种适用于宇航SAR隔离型同步整流电源的防电流倒灌控制方法。通过检测输出电感电流控制副边开关管驱动,实现了副边开关管在输出电感电流过零前断开的功能。仿真和实验结果表明:采用防电流倒灌控制方法后,输出电容阵带电开机时的输出电压波形呈单调上升趋势。该控制方法可有效解决电流倒灌问题,对于提高宇航SAR的综合性能具有重要的实际价值。

A wideband low-phase-noise LC VCO for DRM/DAB frequency synthesizer

The wideband CMOS voltage-controlled oscillator（VCO）with low phase noise and low power consumption is presented for a DRM/DAB（digital radio mondiale and digital audio broadcasting）frequency synthesizer.In order to obtain a wide band and a large tuning range,a parallel switched capacitor bank is added in the LC tank.The proposed VCO is implemented in SMIC 0.18-μm RF CMOS technology and the chip area is 750 μm×560 μm,including the test buffer circuit and the pads.Measured results show that the tuning range is 44.6%;i.e.,the frequency turning range is from 2.27 to 3.57 GHz.The measured phase noise is-122.22 dBc/Hz at a 1 MHz offset from the carrier.The maximum power consumption of the core part is 6.16 mW at a 1.8 V power supply.

Design of a 4.224GHz Quadrature LC-VCO

A 4. 224GHz quadrature voltage-controlled oscillator （QVCO） applied in MB-OFDM UWB synthesizers is implemented in 0.18μm RF-CMOS technology. An improved structure of the QVCO is presented for better phase noise. A novel configuration of a MOS varactor is designed for good linearity of K as well as a new digital capacitor controlled array topology with lower parasitic capacitance and lower Ron. Measurement results show a phase noise of - 90.4dBc/Hz at 100kHz offset and - 116.7dBc/Hz at 1MHz offset from a carrier close to 4. 224GHz. The power dissipation is 10. 55mW from a 1.8V supply.

Highly-compliant,conformal and stretchable microelectrode arrays

Most biological tissues are supple and elastic, while current electronic devices fabricated by semiconductors and metals are usually stiff and brittle. As a result, implanted electronic devices can irritate and damage surrounding tissues, causing immune reaction and scarring. In this work, we develop stretchable microelectrode arrays, with the development of a novel soft lithography technology, which are designed and fabricated with a polymer/stretchable metal/polymer sandwich structure. With the great deformability of stretch, compression, bend and twisting, while preserving electrical property, this technology overcomes the fundamental mismatch of mechanical properties between biological tissues and electronic devices, and provides highly-compliant, confonnal and stretchable bio-electronic interfaces. Here we also describe the following three applications of the stretchable electrode arrays： a. monitoring intracranial electroencephalography （EEG）; b. stimulating peripheral nerves to drive muscles; c. monitoring epicardial electrocardiography （ECG）. Stretchable microelectrode arrays create a promising field in biomedical applications for its better modulus match with biological tissues and robust mechanical and electrical properties. They allow for construction of electronic integrated circuits spread over on complex and dynamic curved surfaces, providing a much friendlier bio-electronic interface for diagnosis, treatment and in- telligent bio-control.

The Velocity Measurement of Two-phase Flow Based on Particle Swarm Optimization Algorithm and Nonlinear Blind Source Separation

In order to overcome the disturbance of noise,this paper presented a method to measure two-phase flow velocity using particle swarm optimization algorithm,nonlinear blind source separation and cross correlation method.Because of the nonlinear relationship between the output signals of capacitance sensors and fluid in pipeline,nonlinear blind source separation is applied.In nonlinear blind source separation,the odd polynomials of higher order are used to fit the nonlinear transformation function,and the mutual information of separation signals is used as the evaluation function.Then the parameters of polynomial and linear separation matrix can be estimated by mutual information of separation signals and particle swarm optimization algorithm,thus the source signals can be separated from the mixed signals.The two-phase flow signals with noise which are obtained from upstream and downstream sensors are respectively processed by nonlinear blind source separation method so that the noise can be effectively removed.Therefore,based on these noise-suppressed signals,the distinct curves of cross correlation function and the transit times are obtained,and then the velocities of two-phase flow can be accurately calculated.Finally,the simulation experimental results are given.The results have proved that this method can meet the measurement requirements of two-phase flow velocity.

In-package P/G planes analysis and optimization based on transmission matrix method

Power integrity (PI) has become a limiting factor for the chip's overall performance, and how to place in-package decoupling capacitors to improve a chip's PI performance has become a hot issue. In this paper, we propose an improved trans- mission matrix method (TMM) for fast decoupling capacitance allocation. An irregular grid partition mechanism is proposed, which helps speed up the impedance computation and complies better with the irregular power/ground (P/G) plane or planes with many vias and decoupling capacitors. Furthermore, we also ameliorate the computation procedure of the impedance matrix whenever decoupling capacitors are inserted or removed at specific ports. With the fast computation of impedance change, in-package decoupling capacitor allocation is done with an efficient change based method in the frequency domain. Experimental results show that our approach can gain about 5× speedup compared with a general TMM, and is efficient in restraining the noise on the P/G plane.

Facile synthesis and excellent electrochemical performance of CoP nanowire on carbon cloth as bifunctional electrode for hydrogen evolution reaction and supercapacitor

In this paper, we report CoP nanowires supported on carbon cloth （CC） （CoP/CC） as a bifunctional electrode for hydrogen evolution reaction （HER） and supercapacitor. CoP/CC possess an excellent electrocatalytic performance for HER, with a Tafel slope of 56 mV/dec and a low overpotential of 68 mV to achieve a current density of 10 mAcm^-2. Remarkably, the bifunctional CoP/CC used as electrode for supercapacitor exhibit a higher specific capacitance of 674 F g^-1 at a scan rate of 5 mV s^-1 and maintains long-life cycling stability, retaining 86% of the initial capacitance after 10,000 cycles. CoP/CC will be a promising candidate as electrode for HER and supercapacitor.

Hierarchical mesoporous Co_3O_4@ZnCo_2O_4 hybrid nanowire arrays supported on Ni foam for high-performance asymmetric supercapacitors

In this paper, hierarchical mesoporous Co3O4@ZnCo2O4 hybrid nanowire arrays（NWAs） on Ni foam were prepared through a two-step hydrothermal process associated with successive annealing treatment. The Co3O4@ZnCo2O4 hybrid NWAs exhibited excellent electrochemical performances with a high specific capacity of 1,240.5 C g^-1 at a current density of 2 mA cm^-2, with rate capability of 59.0%shifting from 2 to 30 mA cm^-2, and only a 9.1% loss of its capacity even after 3,000 cycles at a consistent current density of 10 mA cm^-2. An asymmetric supercapacitor（Co3O4@ZnCo2O4 NWAs｜｜activated carbon） was fabricated and exhibited a high specific capacity of 168 C g^-1 at a current density of 1 A g^-1. And a preferable energy density of 37.3 W h kg^-1 at a power density of 800 W kg^-1 was obtained. The excellent electrochemical performances indicate the promising potential application of the hierarchical mesoporous Co3O4@ZnCo2O4 hybrid NWAs in energy storage field.

Unidirectionally aligned diphenylalanine nanotube/ microtube arrays with excellent supercapacitive performance

High-temperature （150-220 ℃） growth leads to the formation of some peptide nanotube/microtube （NT/MT） arrays but the NTs/MTs exhibit closed ends, irreversible phase modification and eliminations of piezoelectric and hydrophilic properties. Here we demonstrate the fabrication of unidirectionally aligned and stable diphenylalanine NT/MT arrays with centimeter scale area at room temperature by utilizing an external electric field. The interactions between the applied electric field and dipolar electric field on the NTs and surface positive charges are responsible for the formation. The unidirectionally aligned MT array exhibits a supercapacitance of 1,000 μF·cm^-2 at a scanning rate of 50 mV·s^-1; this is much larger than the values reported previously in peptide NT/MT arrays.