The ultimately pure red OLED using new electrophosphorescent compound, bis(2,3-diphenylquinoxaline)iridium(acetylace-tonate) [(QH)2 Ir(acac)] is described. Electrophosphorescence peak wavelength and bandwidth were advanced for the purest red color stimulus to 680nm with full width at half maximum of 89nm by doping (QH)2 Ir(acac) into a light emitting electron transport layer composed of 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole. The most vivid red electrophosphorescence with CIE chromaticity coordinates better than x=0.70 and y=0.28, which are the closest to the ultimate limit of pure red among reported OLEDs, was attained and maintained even in luminance brighter than 600cd/m2. A very high maximum external electrophosphorescent quantum efficiency of 10.2% was also realized.
In this paper, the design of a reconfigurable low-power low-pass Switched Capacitor Delta-Sigma (SC ΔΣ) modulator for GSM/UMTS standards used in an optimum low-IF(LIF)/Zero-IF(ZIF) receiver architecture is described. A new approach for obtaining the optimum modulator coefficients is developed which results in relaxed specifications of the circuit components, aggressive noise transfer function (NTF) and a signal transfer function (STF) with the blocker-rejection property. The modulator employs a second/third-order single-stage dual-quantizer structure. It achieves 85.6dB/57dB SNDR and -0.2dBFS/-0.05dBFS overload factor at 0.2/2MHz bandwidth for GSM/UMTS standards and consumes only 2mW/5mW from a single 1.8V supply in a 0.18µm 1P6M CMOS process. The maximum spread of the modulator capacitors is 105.
A novel polarization controller using the transverse mode switching of a vertical-cavity surface-emitting laser (VCSEL) induced by injection locking is proposed. The operating principle is based on an all-optical inverter using transverse mode switching of an elliptical-shaped VCSEL keeping a stable polarization state. We carried out the modeling based on a multi-transverse-mode rate equation analysis, exhibiting the potential of high-speed polarization control at 5Gbps.
The estimation of OCDMA system performance under the condition of code phase alignment between received and locally generated code signals is demonstrated in dual homodyne correlation receiver using balanced detector. Based on the analysis of auto correlation property for prime codes, distinctive compared to the conventional CDMA codes, the developed model provides a method for interpreting the effect of code synchronization state on the false alarm probability and the corresponding bit error probability. The performance influenced by the chip pulse power and noises is also examined with this model for the cases of single and multiple users.
Switched capacitor filters have been in wide-spread used for a few years, for the realization of stable, accurate and high quality filters for operating frequencies below the megahertz range. This paper would like to prove the feasibility of a novel tuned LC pseudo switched capacitor filter with high quality factor of several hundreds for wireless radio frequency applications. The filter is designed with standard 0.35µm silicon BiCMOS technology. Experimental results at 442MHz switching frequency demonstrate interesting performances; the quality factor is equal to 316 for a frequency bandwidth equals to 1.4MHz.
Testable designs for detecting single stuck-open faults in CMOS circuits have been proposed so that the tests remain valid even in the presence of unequal delays in the circuit. Existing approaches require the CMOS gate to be internally modified and are thus suitable for future chip designs. This paper proposes two versatile designs that can be adapted for both existing chips and new chip designs. A 3-sequence test set and a 2-sequence test set are derived for the proposed designs to reliably detect stuck-open faults.