Modelling the current—voltage characteristic of a fluorescent lamp for computer-aided design

An empirical formula is presented for the voltage-current characteristics of a fluorescent lamp. The three parameters of the formula can easily be obtained from the measured characteristics of the fluorescent lamp without recourse to conventional curve-fitting techniques. By using this formula the analytical study of electronic circuits incorporating fluorescent lamps can be simplified.     

（英）W波段InP HBT 宽带高功率压控振荡器

本文介绍了一款具有较高输出功率和宽调谐频率范围的基波压控振荡器单片集成电路。其制作工艺为f_T =170GHz,f_max =250GHz的0.8um InP DHBT工艺。电路核心部分采用了平衡式考毕兹振荡器拓扑,并在后面添加了一级缓冲放大器来抑制负载牵引效应,并提升了输出功率。DHBT的反偏CB结作为变容二极管来实现频率调谐。芯片测量结果表明,VCO的频率调谐范围为81- 97.3GHz,相对带宽为18.3 %。在调谐频率范围内最大输出功率为10.5 dBm,输出功率起伏在3.5 dB以内。在该VCO的最大调谐频率97.3 GHz处相位噪声为-88 dBc/Hz @1MHz。在目前所报道的InP HBT基VCO MMIC中,本文在如此宽的频率调谐范围内实现了最高的输出功率。     

Brief communication Modelling the static emitter characteristics of unijunction transistors

An empirical formula is presented for the static emitter characteristic of the unijunction transistor (UJT). The three parameters of the formula can be calculated easily from separate regions in the device characteristic using manual calculations.     

Investigation of nonionic diazo dye-doped polymer dispersed liquid crystal film

Sudan black B (SBB) was used to investigate as the nonionic diazo dye-doped in polymer dispersed liquid crystal (PDLC) display, by polymerization-induced phase separation (PIPS) method. The maximum absorbance, contrast ratio, dichroic ratio and the order parameter of nonionic diazo dye in nemetic host (TL203) were investigated using UV?CVis polarized spectroscopy. The orientation of the dye molecules was controlled by electric field, which enabled the contrast ratio of the dye to be obtained by electrically switching. The change occurring on droplet morphologies and electro-optical properties of PDLC film with the change in contents of Sudan black dye and liquid crystals (LC) contents was investigated. We found an increase in LC droplet sizes with the increase of diazo dye and LC contents. Moreover the addition of small amount of nonionic diazo dye reduced the threshold voltage (V $_{\boldsymbol{\rm th}})$ , increased off-state transmittance, enhanced the contrast ratio and decreased the response time of dye-doped PDLC. Additionally the change in transition temperature of LC and changes in LC droplet morphologies with the addition of dye were also observed. Such changes were observed with the images taken by polarized optical microscope (POM). The detail discussions on such behaviours were also made.     

Research Note Two novel voltage( current) controlled integrable oscillators

Two novel voltage( current) controlled oscillator circuits are presented. Each circuit uses a single operational amplifier, a single operational transconductance amplifier, and either a single resistor or a single capacitor. In both circuits the frequency of oscillation can be adjusted by changing the biasing voltage( current) of the operational transconductance amplifier. Experimental results are included     

Prediction of the transient intermodulation performance of operational amplifiers

Closed-form expressions are obtained for the THD, THD-20 and MIM tests used to characterize the TIM performance of operational amplifiers and circuits of similar topology. Good agreement is observed between measured and calculated results. Using approximate formulae for Bessel functions, the calculations can be performed by using small programmable calculators.     

Phototransients in 30 mol% CdO-70 mol% P2O5 glass

Phototransients produced when radiation of wavelength 240 nm is switched on have been studied in (30 mol% CdO-70 mol% P²O⁵ glass at various applied voltages. The phototransients show a linear rise with field, while their decay time (time taken by the photocurrent to attain its steady value) tends to saturate at higher fields. For shorter times ΔIα exp (? t/r), while for longer times there is a departure from the exponential behaviour. These phototransients may be due to trapping of photo-excited charges by ionized donors and space charge effects.     

Harmonic and intennodulation performance of wideband memoryless non-linear amplifiers

By using a different, but equivalent, representation for the general Fourier -series representation, it in shown that the available computer programs, originally designed for in term ovulation analysis of memoryless bandpass nonlinear amplifiers, are adaptable to wideband amplifiers after very minor modifications.