Discrete Cosine Transform for Driving Liquid Crystal Displays

Despite rapid advances in science and technology of liquid crystal display (LCD); elimination of motion-related artifacts and preservation of color purity in moving images have remained elusive because gray-scale to gray-scale response time, i.e., time taken to switch pixels from one gray-scale to another depends on the initial and final gray shades. A technique wherein gray scale to gray scale response times are less dependent on the initial and final gray shades as compared to other addressing techniques for driving matrix LCD is reported. We also found that the response times are about the same as that of a pixel driven with simple square waveforms and, therefore, the effect of duty cycle due to matrix addressing is minimal with distributed waveforms of this technique.      

Trapezoidal and Triangular Waveform Profiles for Reducing Power Dissipation in Liquid Crystal Displays

We propose to replace the rectangular select pulses in all the conventional addressing techniques with either trapezoidal or triangular select waveforms to reduce the power dissipated in rms responding liquid crystal displays. A realistic analysis that includes the distortion in the addressing waveforms is presented for trapezoidal, triangular profiles, as well as their equivalents in discrete domain viz. the multi-step profiles and the results are compared. Good brightness uniformity among pixels that are driven to same state is achieved as a spinoff of the analysis and application of a correction voltage at the end of the select pulses. Increase in hardware complexity and the cost is minimal because just the voltage level generator circuit is modified to achieve reduction in power dissipation with new waveform profiles.     

用于LCD测试系统的程控驱动器设计

为了制作一款用于LCD测试系统的程控驱动器,采用基于嵌入式系统ARM7实现程序控制,内建DC/DC升压电路和DC/AC转换电路,以提供直流电源和产生驱动脉冲信号,电源内建/外接可选,其信号输出端按一定时序产生特定的连续脉冲, 供给LCD 屏的行列电极作驱动源, 从而使被选行与被选列交叉位置上的液晶像素或笔段在电场作用下呈现显示状态（遮光或透光） 。该系统输出的工作电压峰值、频率、占空比均可调,是一款低功耗、低输出阻抗的LCD程控驱动器。     

重复频率及占空比大范围可调的半导体激光器通用电源

介绍了一种多功能通用半导体激光器驱动电源,该电源可以在连续和脉冲两种模式下工作.在脉冲模式下能输出方波、正弦波和三角波,脉冲重复频率和占空比大范围独立可调;采用半导体制冷片作为制冷元件,对激光器工作温度进行控制;同时还采用了防浪涌电路、慢启动电路和过流过压保护等保护电路,从而实现了半导体激光器光功率稳定、可靠、准确输出.该电源已成功地应用于我们研制的增益开关型半导体激光器泵浦的绿光激光器中.     

Low Power Techniques for Gray Shades in Liquid Crystal Displays

The largest transition in the select waveform of successive approximation technique is eliminated to reduce power dissipation in liquid crystal displays. Power dissipation in the driver circuit is analyzed for gray scale images by considering three select sequences. They are compared and a new select sequence is proposed to achieve low power dissipation. An additional pulse is introduced in the select waveform to reduce peak amplitude of select and data waveforms to achieve a low supply voltage for the driver circuit.     

Binary addressing technique with duty cycle control for LCDs

Introduction of duty cycle in the binary addressing technique is proposed to enable integration of liquid crystal display drivers with a digital system in a single chip. An analysis of this technique with duty-cycle control is presented. Effects of duty-cycle control on brightness uniformity of pixels in the liquid crystal display are discussed. A system on chip implementation of the technique is also demonstrated.     

Improved dithering algorithms and its circuit implementing for STN-LCD

1 Introduction STN-LCD is widely used in the small and medium size display field with its developed process, high yield, and low cost, especially for cell phones and personal digital assistant (PDA) [1]. However, the rapid development of global digital co…     

Improved dithering algorithms and circuit implementing for STN-LCD

This article proposes a creative brightness average method to improve the traditional dithering algorithm for super twisted nematic-liquid crystal display (STN-LCD).This method restrains the flicker and crosstalk phenomena by avoiding the simultaneous turning on or turning off between adjacent pixels in the same frame. It costs little hardware to realize the brightness average circuit in the liquid crystal display (LCD) controller, without increasing the complexity of STN-LCD driver circuit. The experimental results show that when the frame frequency is 60 Hz, the monochrome image adds up to 64 gray levels, while the multicolor image adds up to 643= 262 144 colors. Meanwhile, the power consumption of the prototype is only 3 317 mW. In short, the brightness average circuit can restrain the phenomena of flicker in high efficiency, and can remarkedly improve the gray and multicolor effect for STN-LCD without increasing the frame frequency, which leads to an apparent decrease in the power consumption.     

High power laser diode driver based on power converter technology

This paper describes the design of a high speed semiconductor laser diode driver designed for driving 500 mW to 1.5 W diodes at full optical power modulation up to frequencies of 10 MHz. The duty cycle of the modulation may be varied. A switching power-converter based current source allows a higher power delivery efficiency to the diode than in previous designs, allowing for a more modest power supply and dissipation requirements. A dynamic ripple cancellation circuit reduces the power converter output current ripple to less than 1% of full-scale current. The circuit is capable of delivering up to 2.5 A to a laser load, with a 10-90% switching risetime from laser threshold to full on of less than 20 ns     

Self-consistent solutions for allowed interconnect current density.II. Application to design guidelines

We apply the newly developed approach for obtaining self-consistent solutions of the maximum allowed interconnect peak current density as a function of duty cycle, which simultaneously comprehends both electromigration and Joule heating. We demonstrate how to generalize this approach for arbitrary time-varying current density waveforms by introducing an effective duty cycle. We find that bipolar stressing is not always more optimistic than unipolar stressing, depending on the duty cycle. We illustrate worst-case intralevel interactions for multiple leads in a single-level metal system, and show that an effective duty cycle which depends on individual width ratios and duty cycles can be used to determine these worst-case solutions. We also study interlevel interactions in a multilevel metal system. Intralevel and interlevel interactions can cause marked reduction in the maximum allowed peak current density in a lead compared to an equivalent isolated lead, most strongly when its duty cycle is large and the duty cycles of the other interacting leads are small. Complexities due to waveshapes and interactions as described here, coupled with the complexities of real circuit layout and operation, motivate the need for sophisticated circuit simulators which can accurately determine electromigration reliability while self-consistently comprehending Joule heating     

Steady-state analysis of PWM DC/DC switching regulators usingiterative cycle time-domain simulation

A new iterative technique for the steady-state analysis of pulsewidth modulated (PWM) DC/DC switching regulators is presented. The methodology is based on transforming the closed-loop regulator into an open-loop configuration. The steady-state solution is solved by two iteration loops. The first loop is to find the steady-state state variables when the power converter is at a fixed duty cycle. The circuit waveforms are obtained by a stepwise time-domain simulation method, which is based on using stepwise quadratic formulation of the circuit state variables with progressive analysis of the switches' states. The second iteration loop is to determine the steady-state duty cycle of the PWM modulator output, using an explicit “fictitious” ramp offset value as the error index. This two-loop iteration approach lessens the occurrence of the nonconvergence problem that is sometimes found in the single-loop iteration method. Furthermore, the advantages of this method include the following: (1) substantial improvement in speeding up the convergence to steady-state solution; (2) simplicity in requiring simple algebraic manipulations; (3) generality in determining valid topology without prior knowledge of the regulator operation; and (4) directness in determining the switching instants. Several examples illustrating the computational efficiency and the accuracy are presented and are verified with the available literature     

平板显示器驱动芯片高低电压转换电路

LCD、PDP、VFD等各类平板显示器已越来越受到人们关注与喜爱,但大多数平板显示器需要专用的功率驱动芯片来驱动其发光显示,各类专用功率驱动芯片又离不开高低电压转换电路,高低电压转换电路性能的好坏直接影响到驱动芯片的稳定性和功耗等。通过比较平板显示器驱动芯片的几种典型高低压转换电路,设计出一种带有电流源的CMOS型高低压转换电路,它具有最佳的性能指标,该电路不但可以为平板显示器驱动芯片使用,还可以作为其他各类驱动芯片的高低压转换模块使用,最后给出一种具体的平板显示驱动芯片高压CMOS器件结构。     

An AlGaAs/InGaAs pseudomorphic HEMT modulator driver IC with lowpower dissipation for 10-Gb/s optical transmission systems

An optical modulator driver integrated circuit (IC) has been developed for 10-Gb/s optical communication systems. To achieve both high-frequency (HF) operation and low power dissipation, 0.2-μm T-shaped gate AlGaAs/InGaAs pseudomorphic high electron-mobility transistors (HEMTs) have been employed for their large transconductance g_m of 610 mS/mm and high cutoff frequency f_T of 67.5 GHz. In addition, optimizing input logic swing, switching transistor size in the output driver, and using cascode-current mirror circuits with small output conductance enable power dissipation as low as 1 W to be achieved at a 10-Gb/s nonreturn-to-zero (NRZ) signal output with 3 V_p._p. This is the lowest value ever reported for power dissipation. As an additional function, the output-voltage swing can be controlled in the range from 2 to 3.3 V_p._p. by the current mirror circuit for the purpose of adjusting the optical-output-signal duty factor through an optical modulator     

A novel monolithic white LED driver with dual dimming mode

This paper presents a hysteretic-current-control LED driver with the dual dimming mode. This novel monolithic driver includes an output switch and a high-side output current sensing circuit using an external resistor to set the nominal average output current (I_OUTnom). By applying an external control signal to the DIM pin, it can alter flexibly the control mode between the analog (DC) and switching (PWM) dimming. In the DC dimming mode, when the input DC control voltage is adjusted from 0.5 to 2.5 V, the average output current can be changed from 20 to 100 % of the current I_OUTnom. While in the switching dimming mode, the output current is proportional to the duty cycle of the input switching signal and changed from about 0 to 100 % of the current I_OUTnom. The driver circuit has been verified in a 0.5 μm HVCMOS process and the die size is about 1.2 × 1.5 mm². This proposed driver can work in 8–40 V power supply, the maximum average output current is up to 1.0 A.     

小型化低功耗机载显示器图形系统设计与实现

为了满足机载显示器图形生成系统的小尺寸、低功耗需求,提出了一种基于龙芯2K1000的全国产图形生成与处理方案。该方案以2K1000为核心构建硬件平台,使用2K1000内部集成的中央处理器、图形处理器、显示控制器,以及外部的内存实现图形的计算生成和双缓存显示,配合国产可编程逻辑器件实现图形与外视频的叠加显示及机载通信总线扩展。软件上采用航空专用的国产天脉操作系统,基于天脉操作系统设计了关键的图形显示驱动、帧存驱动、显示控制器驱动。实验结果表明,在输出1 024 pixel×768 pixel分辨率显示时,典型机载图形画面帧率达到35 frame/s,整体功耗约10 W。该方案扩展性强、功耗低,满足实时显示需求,在机载显示器领域有着广泛的应用空间。     

A versatile micropower high-voltage flat-panel display driver in a100-V 0.7-μm CMOS intelligent interface technology

A versatile architecture for monolithic low-power high-voltage flat-panel display drivers is presented. A prototype of such a driver chip was designed and fabricated in the 100-V 0.7-μm CMOS intelligent interface technology (I²T) of Alcatel MicroElectronics. It features 100-V output driving capability, while the operation of the entire driver chip is controlled by means of 3- to 5-V digital signals. Special high-voltage level-shifter circuits, based on the dynamic charge control concept, were developed to reduce the internal power consumption of the driver chip to extremely low values of 1 to 2 μW per driver output. A powerful on-chip control unit supports numerous display addressing schemes and very complex multilevel output waveforms can be synthesized. These attractive electrical characteristics, together with the pronounced flexibility and multifunctionality, make this driver architecture ideally suited for a variety of flat-panel displays, especially in battery-powered applications     

An EMI Resisting LIN Driver in 0.35-micron High-Voltage CMOS

This paper describes the design of a local interconnect network (LIN) integrated output driver circuit exhibiting a high degree of immunity against conducted electromagnetic interference (EMI). The transmitted signal of this driver is shaped with a predefined slope so as to reduce electromagnetic emission at higher frequencies. The effect of EMI coupling from the data bus into the driver circuit is countered using a new feedback scheme which shields the slope shaping function from the output stage. Although the output signal may be heavily corrupted by EMI, the LIN driver continues to deliver an unaltered duty cycle, which is mandatory to obtain an error-free data transmission. Measurements show that this driver circuit manages to withstand the highest levels of the direct power injection (DPI) measurements independently of the injected EMI level.     

A 3–8 GHz Delay-Locked Loop With Cycle Jitter Calibration

A 3–8 GHz delay-locked loop (DLL) with cycle jitter calibration is presented. To lower the operation frequency of a voltage-controlled delay line (VCDL), this DLL adopts the dividers, an edge combiner, and the multiple VCDLs. A duty cycle correction circuit is presented to maintain the output duty cycle of 50%. This DLL has been fabricated in 90-nm CMOS process. The measured peak-to-peak jitters at 8 GHz are 11.44 and 6.67 ps before and after calibration, respectively. The power dissipation at 8 GHz is 18 mW for a supply voltage of 1.2 V, and the measured output duty cycle variation is less than 3%.      

一种超级电容储能的双向逆变电路及其控制策略

为解决数控机床加工中意外掉电退刀、伺服单元外接制动电阻产生能耗等问题,提出了一种超级电容储能的双向逆变电路,使得伺服系统在突然断电状态下,储能模块能够继续短时地给数控机床系统供电,完成断电回退的功能。该电路可以提供更高的输出电压和占空比,且在应用中可以取消伺服单元外接制动电阻而将制动能量循环利用,同时提出了相应的控制策略。该电路包括Buck/Boost电路、信号采样电路、PWM逻辑控制电路和互锁驱动电路,通过调节两路互为180°的PWM波占空比及充、放电信号来实现升、降压闭环控制,从而完成能量的双向传递。该拓扑简单、高效,性能稳定,以最少的功率器件实现大功率转换及输出。最后,实验波形验证了所提方案的可靠性。     

非制冷微测辐射热计受激光辐照的温度响应

红外成像技术的不断革新使得非制冷微测辐射热计在军用侦察装备当中逐渐普及,其激光干扰技术的研究也成为热点,而探测器像元受到激光辐照的温度响应是干扰成功的关键。围绕斩波调制的激光辐照微测辐射热计的温度响应问题,立足UL01011型非晶硅探测器建立了模型,并通过有限元分析的方法研究了调制频率、占空比和激光功率三个参数各自对温度增量的影响。通过分析推导得出结论:功率稳定的连续激光经斩波调制后辐照至非制冷微测辐射热计时,稳定状态下像元温度升高量的振荡均值,与调制频率成负指数关系,与占空比成正指数关系,与激光功率成倍率关系。