Fuzzy logic based temperature control of thermoelectric cooler (TEC) for single photon avalanche diode (SPAD) application

Single photon avalanche diode (SPAD) is a temperature sensitive device. Even a slight variation of temperature can cause unstable performance in quantum efficiency, responsitivity and dark counts. Due to these reasons,unstable temperature could cause overall poor performance of SPAD. It is common for thermoelectric cooler (TEC) to be used as cooling of photodetectors. SPAD was mounted onto the TEC where it needs to be maintained at a constant low temperature under variation of ambient temperature. The system is simulated using Fuzzy Logic Toolbox in MATLAB Simulink. Simulated using P-type fuzzy logic with the set point temperature of 20˚C and ambient temperature of 16˚C, produce a result of -19.44˚C. The P-type fuzzy logic control design has shown a good overall performance where the steady state error is ±0.56˚C, which is equivalent to ±2.8% and the settling time for the output simulation, ts, is 35.91s

Investigation of Current Leakage Mechanisms on InAs Nanoisland Diodes for Radiation Hardness

This research project presents the effects of thermal neutron radiation of fluences ranging from 3 to 9×1013 neutron/cm2 on the electrical behaviour of quantum dot-in-a-well semiconductor samples. The samples are characterized via forward-bias and reverse-bias current densities measurement, capacitance-voltage measurement and temperature dependence measurement. After neutron irradiation of up to 9×1013 neutron/cm2, the leakage current increases both in forward bias and reverse bias by an order of magnitude and two orders of magnitude respectively. Increments are expected to be due to the induced displacement damage effect. Based on ideal diode equation fitting, the ideality factor and series resistance are some of the values that increase with the increasing neutron fluence, indicating a change in the current transport mechanism as well as the doping profile. From the capacitance-voltage measurement, the capacitance is calculated to reduce by up to 6.42%, which is believed to be due to the carrier removal effect. Reduction in the doping densities of the p-region and i¬-region and increment in the doping densities of the n-region on the other hand suggests an effect of Neutron Transmutation Doping. An insight on the reverse-bias leakage current mechanism reveals that the increase in current densities is due to trap-assisted generation-recombination and Frenkel-Poole effect

Degradation of InGaN LEDs by proton radiation

Light-emitting diodes (LEDs) made of nitride are appealing because they can withstand high temperatures and be used in harsh environments. The degradation behaviour of the device performance on Indium Gallium Nitride (InGaN) LEDs (light emitting diodes) irradiated by 2-MeV protons with the fluence of 1x 1013 cm-2 is studied. The electrical and optical characteristics of three commercially available LEDs, VLHW4100, OVLAW4CB7 and VAOL-3GWY4, were compared before and after radiation. The results show a considerable degradation in the LED electrical performance. After irradiation, the reverse leakage current increases in all three devices. The degradation in OVLAW4CB7 is for the entire reverse bias voltage range, while the degradation is prominent at lower reverse bias voltages for the other two devices. However, while calculating the increase in dark current at a reverse bias voltage of 5 volts, it is found that the dark current increases the most in VAOL-3GWY4, which is around 22 times. The traps and the bulk defect are believed to contribute to the increased leakage current. The forward Current-Voltage and the Capacitance-Voltage characteristics do not change much after radiation. The optical intensity corresponding to different wavelengths is obtained for the device's optical characterization. The results show that the optical intensity of the devices increased after radiation. This increase is because of the increase in carrier lifetime in the active region after radiation and radiation-induced annealing of defects. In this research quantum well LEDs are used. When using these devices based on InGaN in harsh conditions or open spaces, the degradation characteristics described in the present study can assist scientists and engineers in making well-informed decisions, as little is known about the degradation of InGaN LEDs after proton radiation

Noise sources extraction for conducted emission modeling of IC’s using IBIS models

The proper functioning of an Integrated Circuit (IC) in an impeding Electromagnetic environment has always been a major concern. Electromagnetic Interference (EMI) can cause an IC to malfunction or give erroneous results. This becomes even a bigger concern for IC’s that are used in automotive industry. Automotive industry in particular, the smart vehicle, is facing design challenges such as susceptibility towards Electromagnetic Interference (EMI). The growing numbers of IC’s on the electronic modules in smart automotive industry creates demand on Electromagnetic Compatibility (EMC) compliance. This EMC is driven by preventing Electromagnetic Interference (EMI) malfunctions within a vehicle. Failure to prevent this could result in fatal accidents. This paper introduces the basic concepts related to the Electromagnetic Compatibility (EMC) of integrated circuits (IC’s). An overview of methods to evaluate EMC of an IC’s has been provided and a methodology to extract noise sources using IBIS model of IC’s is introduced in this paper. Cosimulations are carried out between ANSYS HFSS and Agilent ADS. Noise sources for conducted emission modelling have been extracted

Signal integrity analysis and noise source extraction of integrated circuits using IBIS models

Integrated Circuits (ICs) play a critical role in an electronic system's Electromagnetic Compatibility (EMC). Generally, ICs are the ultimate source of interference-causing signals and noise. Signal Integrity in ICs also poses increasing challenges to PCB designers. Analyzing the Signal Integrity issues at the upfront design level before the prototype board is fabricated is important. Electromagnetic Compatibility (EMC) improves significantly for a board that undergoes Signal Integrity analysis. The use of electronic equipment in the Automotive Industry has been increasing ever since. On an average a smart car contains over 50 ICs. This scenario creates a demand for EMC compliance of ICs used in Automotive Industry. Failure to make the ICs Electromagnetic Compatible could result in fatal accidents. This paper introduces the basic concepts of EMC of IC’s. A methodology to perform the Signal Integrity analysis and extract noise sources from the ICs using IBIS models has been presented. Co-simulations are carried out between ANSYS HFSS and Agilent ADS