Low-voltage silicon(Si)-based light-emitting diode(LED) is designed based on the former research of LED in Si-based standard complementary metal oxide semiconductor(CMOS) technology.The low-voltage LED is designed under the research of cross-finger structure LEDs and sophisticated structure enhanced LEDs for high efficiency and stable light source of monolithic chip integration.The device size of low-voltage LED is 45.85×38.4(μm),threshold voltage is 2.2 V in common condition,and temperature is 27 ℃.The external quantum efficiency is about 10-6 at stable operating state of 5 V and 177 mA.
We experimentally demonstrate a high-speed phosphorescent white light emitting diode(LED) visible light communication(VLC) system without utilizing an optical blue filter. Here, the white light response is equalized by using the proposed analog equalizers. The 3 d B bandwidth of the VLC link could be extended from 3 to132 MHz, which allows 330 Mbit/s non-return-to-zero on–off keying(NRZ-OOK) data transmission with a bit error ratio(BER) of 7.2 × 10-10 and 672 Mbit/s 64-quadrature amplitude modulation(64-QAM) data transmission with a BER of 3.2 × 10-3. These resultant BERs are less than the forward error correction(FEC) limit of3.8 × 10-3. The VLC link distance is 1 m using a single 1 W LED. The transmitter and receiver modules are integrated to a compact size. Furthermore, the relationships between the signal performance and illumination level or optical power are investigated and analyzed.
TiN,platinum (Pt) black and iridium oxide are introduced to the stimulating sites to improve the performance of the flexible electrode.Low temperature process is used to fabricate the modifying films.TiN is coated on the gold sites by magnetron sputtering while platinum black and iridium oxide are coated by electroplating and electrodeposition,respectively.The im-pedance of the electrode decreases dramatically after modification.The combined analysis of surface morphology and cyclic voltammograms (CV) in phosphate buffer saline (PBS) solution indicates that the modified electrode sites have larger elec-trode-electrolyte capacitance and smaller faradic resistance than unmodified sites,thus they have smaller electrochemical im-pedances.
LI XiaoQianPEI WeiHuaTANG RongYuGUI QiangGUO KaiWANG YuCHEN HongDa
We present a high-speed visible light communication(VLC) link that uses a commercially available phosphorescent white light-emitting diode(LED). Such devices have few megahertz bandwidth due to the slow response of phosphorescent component,which severely limit the transmission data rate of VLC system. We propose a simple pre-emphasis circuit. With blue-filtering and the pre-emphasis circuit,the bandwidth of VLC system can be enhanced from 3 to 77.6 MHz,which allows non-return-to-zero on-off-keying(NRZ–OOK) data transmission up to 200 Mb/s with the bit error ratio of 5.3 × 10-7 which is below 10-6. The VLC link operates at the room illumination level of ~1000 lx at 1.1 m range using a single 1 W white LED.
This paper presents a modified regulated cascode(RGC) transimpedance amplifier(TIA) with a novel pre-equalized technique. The pre-equalized circuit employed the broadband series inductive-network and Gmboosting technique. The introduction of this technique compensates the transferred signal at the input port of the TIA without an increase in power dissipation. Furthermore, a novel miller capacitance degeneration method is designed in the gain stage for further bandwidth improvement. The TIA is realized in UMC 0.18 m CMOS technology and tested with an on-chip 0.3 p F capacitor to emulate a photodetector(PD). The measured transimpedance gain amounts to 57 d B with a 3 d B bandwidth of about 8.2 GHz and consumes only 22 m W power from a single1.8 V supply.
