Wei-Dar Chen

A Miniaturized Electromagnetic Generator With Planar Coils and Its Energy Harvest Circuit

This study presents design, analysis and experiment of a miniaturized rotary generator in size of 10 times 10 times 2 mm3 and its compact energy harvest circuit chip. The designed generator consists of patterned planar copper coils and a multipolar hard magnet ring made of NdFeB. To perform modeling, a harmonic-like magnetic field model along the circumferential path of each magnetic pole is assumed with the assistance from measured peak magnetic flux densities. This is followed by the application of Faradays law to predict generated electromotive forces (EMFs) in terms of the relative rotational speed between the magnet ring and coils. The genetic algorithm (GA) is next applied to optimize the critical dimensions of the miniaturized generator. The theoretical model of this power microgenerator is evaluated and compared with experimental results, and it is found that the analytical simulation shows a good agreement with the experimental results. The optimized generator offers 4.5 V and 7.23 mW in root mean square (rms) at 10 000 r/min. With microgenerator successfully fabricated, a novel energy harvest circuit employing Dickson charge pump is designed and fabricated via the 0.35-mum process offered by National Chip Implementation Center (CIC) of Taiwan. This charge pump circuit owns the merit of almost-zero thresholds of employed metal-oxide-semiconductor (MOS) transistors, enabling the conversion of low-power alternating current (ac) signals by the microgenerator to direct current (dc) ones.

A multi-touch interface circuit for a large-sized capacitive touch panel

This study presents a multi-touch sensing circuit for large-sized (more than 12 inches) capacitive touch panel. A new AC sensing technique is developed to enable the touch sensing in a large-sized capacitive touch panel. This novel designs of multi-touch sensing circuit lies in the operation principles through a 4×4 ITO film sensor array, a low-disturbance array circuit, a capacitance to voltage converter circuit and the proposed design procedure of chip parameters by circuit simulation. Furthermore, the sequence control for the array is generated by an FPGA module to accomplish the operation of the whole circuit. Some of objectives are to reduce environmental disturbance of the panel and to distinguish multi-touching locations from the panel. The corresponding output voltages of multi-touch sensing circuit are output in proportional to location touched by a human finger. Finally, the whole circuit is implemented by using TSMC 0.35µm 2P4M process. The circuit output voltages are used to distinguish touch locations by a proposed algorithm.

A New Compensation Method for Emission Degradation in an AMOLED Display Via an External Algorithm, New Pixel Circuit, and Models of Prior Measurements

A new external algorithm with sensing circuit are proposed to compensate AMOLED display degradation. The compensation is enabled by first evaluating degradation level of OLEDs based on the OLED anode voltages detected by a newly-designed sensing subcircuit. According to sensed voltages, the external algorithm selects appropriate built-in models to compensate OLED degradation with the aim to achieve expected OLED emitted luminance. The models are established based on prior measurements to prescribe the relations between luminance and current (L-I) and luminance and voltage (L-V) of each OLED. In this way of compensation, the proposed method is able to incorporate negative effects of OLED degradation aggravation while increasing driving current to compensate the original decay in OLED luminance. Moreover, another algorithm along with the 4T0.5C pixel circuit as presented in prior studies are adopted to compensate process variation in Vth among pixels for improving the emission uniformity of an AMOLED panel. Experiments are conducted by combining the external algorithm with sensing circuit and the pixel circuit to validate the performances of compensating and alleviating OLED degradation.

A novel 3D optical proximity sensor panel and its readout circuit

This study presents a novel 3D optical proximity sensor (3D OPS) array panel. The panel is capable of detecting the objectives centimeters away from the panel surface. This device is composed of light-emitting diodes and home-made polymer photo-detectors (PPDs). The novel design of the circuit is the operation principle through active pixel circuit, sampling circuit, amplifier circuit and the decision of proposed chip parameters is determined by circuit simulation. The circuit is regarded low power and low cost as the design principle. The control sequence of the aforementioned circuit module is generated by an FPGA board to realize the operation of the whole circuit. The readout circuit is able to remove background current, and to detect the corresponding output voltage of photocurrent that is received by the PPD via reflections of the measured object. A human machine interface is built by LABVIEW to create 3D vision tracing of sensed object, validating the effectiveness of the 3D OPS.

Effects of hydrogenation on electrical properties of InP grown on GaAs by the photochemical vapor deposition system

Effects of hydrogenation on electrical properties of InP epilayers grown on GaAs substrates by ‘photochemical vapor deposition’ have been investigated. The electrical properties were characterized by current-voltage and capacitance-voltage measurements at room temperature. Deep level transient spectroscopy technique was used as an auxiliary method to detect the deep level traps. Hydrogen plasma exposure at 250 “C for 3 h increased the reverse breakdown voltage by a factor of about 1.7 and the Schottky barrier height by 0.05 eV. In addition, the shallow and deep levels were substantially passivated. These results indicate that hydrogenation by the phot~hemi~l vapor deposition system for InP on GaAs is an excellent method to improve its device application,

Design and Realization of High Resolution (640×480) SWIR Image Acquisition System

Imaging technology has been in revolutionary progresses in decades with well-developed semiconductor and memory industries. Silicon sensors are used in most of camera and DV, since silicon is the best material for visible light imaging (wavelength from 400nm∼700nm). Short wave infrared (SWIR) requires indium gallium arsenide (InGaAs), composed of chemical compounds including indium arsenide (InAs) and gallium arsenide (GaAs), to cover SWIR spectrum. Wavelength of typical SWIR is defined between 0.7um and 2.5um; SWIR cameras focus on wavelength between 0.9um∼1.7um (In0.53Ga0.47As). Unlike Mid-Wave IR and Long-Wave IR, SWIR is reflected and absorbed by objects, which advantages SWIR imaging higher resolution due to better contrast. SWIR also has excellent imaging quality in low illumination environment and moon light or star light are good emitters outdoor at night. Another primary characteristic of SWIR is high penetration, providing effective imaging under hazy conditions. An Example for night vision between SWIR.Copyright