Browsing by Author "Chao, Paul C-P"

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A low-power reference-less clock/data recovery for visible light communication devices requiring low data throughput
(2020-01-01)
Liu, Ming-Cheng
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Pribadi, Eka Fitrah
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Chao, Paul C-P
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Pandey, Rajeev Kumar
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電子工程學系及電子研究所
In this study a reference-less clock and data recovery (CDR) is designed and developed for the low speed visible light communication system based Internet of Things (IoT) tags. Design system incorporates an off-chip photodiode and an integrated-on chip front-end receiver with the reference-less CDR. For an IoT tags low power consumption, low supply voltage, and small area are the major design constraint. Considering these constraints, the circuit of the front-end receiver incorporate the near-threshold cascode current mirror based transimpedance amplifier, low pass filter and a comparator. On the other-hand, low power all-digital phase locked loop-based reference-less CDR is design herein with a modified loop filter, auto tune digital control oscillator and auto duty cycle adjustment circuit. The circuit is implemented in an integrated chip with area of 0.728 mm(2) via TSMC 180 nm process. Experimental measurement results of the tapeout chip shows that the phase noises are - 39.54 dBc/Hz @ 1 kHz, - 80.35 dBc/Hz @ 10 kHz and - 92.26 dBc/Hz @ 100 kHz. The measured jitter in the recovered clock is 3.312 ns (0.0033 UI). At 1 Mbps, the measured total power consumption is 5.58 mu W. The achieve results shows that the implemented circuit in this study highly support the commercial low data rate based optical wireless sensing nodes for IoT tags.
A New Cuffless Optical Sensor for Blood Pressure Measuring with Self-Adaptive Signal Processing
(2016-01-01)
Kao, Yung-Hua
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Chao, Paul C-P
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Tu, Tse-Yi
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Chiang, Keng-Yueh
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Wey, Chin-Long
A new cuffless, wireless optical blood pressure (BP) sensor is successfully developed by this study. This device employs the technique of photoplethysmograph (PPG) to read out in real time the intravascular blood volume change and then to calculate BP. The system utilizes a red-light LED with a wavelengths of 660 nm. The readout circuit includes a pre-amplifier, a band-pass filter, a programmable gain amplifier (PGA), an Arduino unit for calculation and a Bluetooth module for wireless communication. A notebook or a mobile phone is also used to display continuous BPs and conducts statistical analysis/results. The passband is from 0.3 to 3.4 Hz. The range of adjustable gain are from 60 to 80 dB. Measured PPGs of different subjects can be auto-adjusted with varied gain by a PGA with a pre-designed digital circuit. In results, the signal-to-noise ratio (SNR) is improved for accurate estimates on BPs. 8 subjects participated in the experimental validation, in which the obtained BPs are compared with the results from a commercial blood pressure monitor by OMRON. The maximum error of experimental results is +/- 6 mmHg, which is less than 8 mmHg conforming to the requirement by the Advancement of Medical Instrumentation (AAMI). This study pioneers to report stable, accurate estimates on BPs by a cuffless optical hand-held device.
A new energy harvest system with a hula-hoop transformer, micro-generator and interface energy-harvesting circuit
(2011-06-01)
Chao, Paul C-P
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Shao, C. I.
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Lu, C. X.
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Sung, C. K.
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影像與生醫光電研究所
This study presents a synthesis of a new energy harvest system that consists of a hula-hoop transformer, a micro-generator and an interface energy harvest circuit. The hula-hoop transformer mainly comprises a main mass sprung in one translational direction and a free-moving mass attached at one end of a rod, the other end of which is hinged onto the main mass. The transformer is capable of transforming linear reciprocating motions to rotary ones based on the concepts similar to the hula hoop motions. The transformer is subsequently integrated with a miniaturized rotary generator in size of 10 9 10 9 2 mm 3 and its compact energy harvest circuit chip. The designed generator consists of patterned planar copper coils and a multi-polar hard magnet ring made of NdFeB. The genetic algorithm (GA) is next applied to optimize the critical dimensions of the miniaturized generator. The optimized generator offers 4.5 volt and 7.23 mW in rms at 10,000 rpm. With micro-generator successfully fabricated, a novel energy harvest circuit employing a new dual phase charge pump, power management circuit, a low dropout regulator and battery charger is designed and fabricated via the 0.35 mu m process. This charge pump circuit owns the merit of automatic conversion of low-power AC signals by the micro-generator to DC ones. Experiments were conducted to show the favorable performance of the proposed energy harvest system. This is the first work that invents a motion transformer from ubiquitous reciprocating to rotational motions. In this way, higher-efficient energy conversion via compact-sized rotational electromagnetic generators can be realized as opposed to popular piezoelectric structures.
A NEW GAS BIO-SENSOR IN THE STRUCTURE OF A MICRO-MACHINED CLAMPED-CLAMPED INERTIAL BEAM AND ITS READOUT CIRCUIT
(2012)
Xue, Bing-Ze
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Chao, Paul C-P
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Lin, Bor-Shyh
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Tsai, Chun-Yin
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Chen, Tsung-Lin
This study presents a novel gas bio-sensor in the form of a micro-machined resonator and its readout circuit. The resonator has the structure of a clamped-clamped beam with thermal actuation and piezo-resistive sensing that supports a plate capable of being attached with test gas molecules to detect gas concentration. The purpose of this study is to design and fabricate the micro-scaled inertial beam with its readout circuit in a system-on-chip package. The circuit includes a driver, a front-end converter, a feed-trough reduction unit, a square-wave converter and a phase detector. In the process of signal reading,, the sensor is first driven by a DDS module and power amplifier, and then sense the vibrations by piezo-resistivity. The piezo-resistivity is detected by a Wheatstone bridge circuits. The carried signal of modulation is processed by a Wheatstone bridge circuits. An instrumentation amplifier adjusts the gain to the appropriate amplitude. The circuit with reduction on feed-through noise increases the SNR. Square wave conversion circuit and PFD process the signal and the driver reference signal to detect phase difference. The data of phase difference is counted into a microcontroller dsPIC4011 and then the data being transmitted to the computer by RS232 to a USB adapter. Finally, the whole circuit is implemented by using TSMC 0.35 2P4M process and one-step post-processing.
A New Method for Calibrating a Six-DOF Joint Force/Torque Sensor
(2014-01-01)
Tran Trong Hieu
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Chao, Paul C-P
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Wang, Yu-Jen
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Wang, Chun-Chieh
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電機工程學系
A New Prediction Model on the Luminance of OLEDs Subjected to Different Reverse Biases for Alleviating Degradation in AMOLED Displays
(2014-01-01)
Chao, Paul C-P
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Hsu, Yen-Ping
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Kao, Yung-Hua
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Lee, Kuei-Yu
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電機工程學系
A new two-DOF rotational optical image stabilizer
(2011-06-01)
Chao, Paul C-P
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Chen, Yu-Han
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Chiu, Chi-Wei
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Tsai, Meng-Yen
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Chang, Jyh-Yeong
This work proposes design, optimization and validation of a new two degree-of-freedom (DOF) rotational optical image stabilizer (OIS) that is suitable for installing into a mobile-phone-camera. This OIS differs from the previous designs since it stabilizes the lens holder directly by two-DOF translational mechanisms that are actuated by voice coil motors. The work can be divided into three main parts: (1) designs of mechanism and genetic algorithm (GA) optimization of magnetic field, (2) establishments of the dynamic model and equation of motions (EOM) of a dual-axis rotational structure, and (3) realizations of a sliding mode control (SMC) controller with fine performance. The dynamic of the dual-axis rotational OIS system has been analyzed and the EOM has been derived. Based on the Lagrange's method, the motions of the OIS have been modeled through considering kinetic energy and electromagnetic torques. In the last part, the theory of SMC is applied, and the associated simulations are conducted. Based on the simulation results, the SMC controller is forged with the assistances from MATLAB pre-simulation and tested by a microprocessor module. After a series of experiments and verifications, the prototype of the novel OIS is finally accomplished with satisfactory performance of vibration reduction.
An efficient energy harvesting circuit for batteryless IoT devices
(2020-01-01)
Yang, Ching-Cheng
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Pandey, Rajeev
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Tu, Tse-Yi
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Cheng, Yuan-Po
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Chao, Paul C-P
A new energy harvesting circuit for battery-less IoT beacon tags is developed herein to maximize power conversion efficiency as well as high throughput power with a wide input-output range. This design energy harvest (EH) circuit incorporates a charge pump (CP) with shoot-through current suppression, a body selector circuit, a maximum power point tracking circuit (MPPT), a timing control circuit, a hysteresis control circuit and a low dropout regulator. Also in this MPPT circuit is a gated clock tuned in a self-adaptive fashion to match the input impedance of the EH circuit to the output impedance of the photovoltaic (PV) panel, thus achieving successfully maximum power point. The circuit is implemented in an integrated chip in an area of 1.2 mm(2) via the TSMC 0.18 process. Experiments on the chip are conducted and the results show that the input voltage range is allowed from 0.55 to 1.7 V to effectively harvest the solar power from a flexible dye-sensitized solar cell. The achieved peak power conversion efficiency (PCE) is 77% at the input power of 52 mu W. For a wide range of lighting luminance (300-1300 lx,) the achieved average PCE is more than 70%. The achieved wide input-output range and the maximum throughput power of 200 mu W is much larger than others reported, while the 77% of PCE is close to that best power conversion efficiency reported.
An Optimized On-Chip Boost-type DC-DC Converter with an On-board Inductance
(2014-01-01)
Chao, Paul C-P
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Kuan, Ching-Hua
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Su, Jia-Wei
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影像與生醫光電研究所
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電機工程學系
Control Design and Digital Implementation of a Fast 2-Degree-of-Freedom Translational Optical Image Stabilizer for Image Sensors in Mobile Camera Phones
(2017-10-01)
Wang, Jeremy H-S
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Qiu, Kang-Fu
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Chao, Paul C-P
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電控工程研究所
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Institute of Electrical and Control Engineering
This study presents design, digital implementation and performance validation of a lead-lag controller for a 2-degree-of-freedom (DOF) translational optical image stabilizer (OIS) installed with a digital image sensor in mobile camera phones. Nowadays, OIS is an important feature of modern commercial mobile camera phones, which aims to mechanically reduce the image blur caused by hand shaking while shooting photos. The OIS developed in this study is able to move the imaging lens by actuating its voice coil motors (VCMs) at the required speed to the position that significantly compensates for imaging blurs by hand shaking. The compensation proposed is made possible by first establishing the exact, nonlinear equations of motion (EOMs) for the OIS, which is followed by designing a simple lead-lag controller based on established nonlinear EOMs for simple digital computation via a field-programmable gate array (FPGA) board in order to achieve fast response. Finally, experimental validation is conducted to show the favorable performance of the designed OIS; i.e., it is able to stabilize the lens holder to the desired position within 0.02 s, which is much less than previously reported times of around 0.1 s. Also, the resulting residual vibration is less than 2.2-2.5 m, which is commensurate to the very small pixel size found in most of commercial image sensors; thus, significantly minimizing image blur caused by hand shaking.
dc dynamic and static pull-in predictions and analysis for electrostatically actuated clamped circular micro-plates based on a continuous model
(2010-02-01)
Liao, Lun-De
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Chao, Paul C-P
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Huang, Chih-Wei
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Chiu, Chi-Wei
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影像與生醫光電研究所
This study develops a continuous model to analyze the 'pull-in' effect in the circular micro-plates used in capacitive-type micro-electro-mechanical systems (MEMS) sensors, actuators and microphones. In developing the model, the governing equation of motion of the deformed plate is established in the form of a partial different equation (PDE) which is then decomposed using the Galerkin method to create a coupled set of modal ordinary differential equations. By considering the first-order deflection mode only and using a fifth-order Taylor series expansion of the electrostatic force, closed-form solutions are obtained for both the position and the voltage of the static pull-in event. Applying an energy balance method and a finite-order approximation method, the solutions are then obtained for the position and voltage of the dynamic pull-in event. The theoretical results obtained for the pull-in phenomena are verified based on the comparison to available experimental data, and also numerically using a finite element analysis (FEA) approach. In general, the results indicate that the ratio of the dynamic to static pull-in voltages is approximately 92%. However, when the squeezed-film effect induced by the air gap between the two plates is taken into account, the value of this ratio increases slightly as a result of considering a higher dynamic pull-in voltage.
DC dynamic pull-in predictions for a generalized clamped-clamped micro-beam based on a continuous model and bifurcation analysis
(2008-11-01)
Chao, Paul C-P
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Chiu, C. W.
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Liu, Tsu-Hsien
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電控工程研究所
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Institute of Electrical and Control Engineering
This study is devoted to providing precise predictions of the dc dynamic pull-in voltages of a clamped-clamped micro-beam based on a continuous model. A pull-in phenomenon occurs when the electrostatic force on the micro-beam exceeds the elastic restoring force exerted by beam deformation, leading to contact between the actuated beam and bottom electrode. DC dynamic pull-in means that an instantaneous application of the voltage ( a step function such as voltage) is applied. To derive the pull-in voltage, a dynamic model in partial differential equations is established based on the equilibrium among beam flexibility, inertia, residual stress, squeeze film, distributed electrostatic forces and its electrical field fringing effects. The method of Galerkin decomposition is then employed to convert the established system equations into reduced discrete modal equations. Considering lower-order modes and approximating the beam deflection by a different order series, bifurcation based on phase portraits is conducted to derive static and dynamic pull-in voltages. It is found that the static pull-in phenomenon follows dynamic instabilities, and the dc dynamic pull-in voltage is around 91-92% of the static counterpart. However, the derived dynamic pull-in voltage is found to be dependent on the varied beam parameters, different from a fixed predicted value derived in past works, where only lumped models are assumed. Furthermore, accurate closed-form predictions are provided for non-narrow beams. The predictions are finally validated by finite element analysis and available experimental data.
Design and development of a wireless fall detection module for homecare
(2014-01-01)
Chao, Paul C-P
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Hsu, Li-Chi
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Li, Yu-Feng
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Chun, Chin-Wei
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電機工程學系
Design and implementation of a new high-accuracy interpolation encoder IC for magneto-resistive sensors
(1970-01-01)
Chen, Wen-Yu
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Chang, I-Feng
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Chao, Paul C-P
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Thakur, Smriti
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Tu, Tse-Yi
A new algorithm named the eight-section (ES) method for carrying out the interpolation for a magneto-resistive (MR) encoder is successfully developed and fabricated in a digital chip. It is known that a conventional magneto-resistive (MR) encoder employs the interpolation method, which converts incoming front-end analog signals in harmonics in sinusoids/co-sinusoids to moving displacement via calculating arc-tangents. This conventional interpolation requires divisions to be carried out for the displacement, which often leads to large noises while conducting digital computation, eventually undermining significantly the accuracy of the MR sensor. The proposed interpolation of eight-section (ES) is designed specially without divisions in the digital computation, leading to higher precision than the conventional interpolation conducting the computation of arc-tangents. The digital computation chip designed by this study consists of a cycle counter, two decimators for incoming analog signals of the MR sensor, a correcting circuit, and the proposal ES interpolation unit. The designed chip is successfully fabricated by TSMC 0.18-mu m CMOS process, the area of which is 1643 x 1676 mu m. The chip is than calibrated by a reference interferometer by experiments for further improving the measurement accuracy. The precision finally results in measuring displacement reaches as accurate as within 1.065 mu m, which is much favorable to the existing performance around 2 mu m by the conventional interpolation.
Design and Validation of a New PPG Module to Acquire High-Quality Physiological Signals for High-Accuracy Biomedical Sensing
(2019-01-01)
Kao, Yung-Hua
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Chao, Paul C-P
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Wey, Chin-Long
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
A new photoplethysmography (PPG) module is designed, optimized, and fabricated in this study to obtain quality PPG signal for high-accuracy bio-sensing. The module contains four light emitting diodes (LEDs) in wavelengths of 530, 660, 850, and 940 nm and a photo-diode (PD). The distances between LEDs and PD are optimized for quality PPG signals via maximizing the ratios of pulsatile (ac) to non-pulsatile (dc) components in PPG waveforms. The optimization is carried out based on an establishment of a complete optical model that simulates well optics under the user's skin based on Beer-Lambert law. In results, the optimal LED/PD distances that lead to maximal ac/dc ratios of PPGs for different wavelengths are derived. With the optimal LEDs/PD distances in hand, a new PPG module is designed and fabricated subsequently, and further installed in a hand-held blood pressure (BP) sensing device for performance validation. Based on experimental results, for the PPG module, an ac/dc ratio of 8.02% is achieved by the proposed PPG module as opposed to 6.74% and 6.90% by two other commercial modules. As for sensing BP based on reflective pules transient time, the error is controlled well with the mean difference (MD) and standard deviation (SD) as -1.16 +/- 5.38 (MD +/- SD) and -0.53 +/- 1.92 mmHg, respectively, for systolic blood pressure and diastolic blood pressure. The resulted accuracy successfully categories the developed PPG sensor among the bests by Association for the Advancement of Medical Instrumentation and British Hypertension Society.
Modeling and analysis of touch on flexible ultra-thin touch sensor panels for AMOLED displays employing finite element methods
(2017-11-01)
Chou, Kuo-Yu
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Chao, Paul C-P
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Chen, Chuan-Xin
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Wu, Chang-Xian
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Huang, Sheng-Chieh
The work employs the finite element method (FEM) to model the touch on the flexible ultra-thin touch sensor panel for analyzing touch characteristics and signals. Touch sensor panel readout circuits typically depend on touch signals to determine whether the touch sensor panel is touched or not. However, the ultra-thin touch sensor panel encountered a problem which cannot correctly recognize touch points on this type of touch sensor panel (TSP) on active-matrix organic light emitting diodes (AMOLED) displays since its electrical characteristics are different from the one of the conventional TSP. The modeling techniques for the flexible ultra-thin touch sensor panel on an AMOLED display is used to analyze touch signals from the influence of the thickness of top over layer of the flexible ultra-thin TSP and to observe the variations of mutual capacitance from touch on the flexible ultra-thin TSP. When the flexible ultra-thin touch sensor panel with the thickness of the top over layer less than the threshold thickness of the top over layer is on multi-touch, the phenomenon of the ghost points are generated. The simulation to find the threshold thickness of the top over layer based on the FEM model is conducted, and the simulation results show the top layer thickness should be larger than 107 A mu m to eliminate the ghost points. Furthermore, a new solution that is an optimization of the electrode pattern of transmitters and receivers in the ultra-thin touch sensor panel to further minimize the threshold thickness of the top over layer of TSP without changing the physical structure of TSP is proposed. The results conducted by using this proposed solution show that TSP top over layer threshold thickness can be reduced to 65 A mu m without appearance of the ghost points.
Optimal Design of a New Strain-Type Sensor for Cuff-Less Blood Pressure Measurement via Finite Element Modeling and Taguchi Method
(2019-11-15)
Tu, Tse-Yi
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Chao, Paul C-P
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電機工程學系
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電控工程研究所
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Department of Electrical and Computer Engineering
A new cuff-less blood pressure (BP) sensor is designed and optimized in this paper. This BP sensor is in a shape of a circular disc of polymer enclosing an electrode. As the sensor is attached to the wrist artery, the dynamic bending of the sensor due to small artery pulsation induces variation in the electrode strain, and then, its resistance varies. With adequate amplification to sense resistance variation, the pulsation signals can be successfully obtained. With the measured pulsation representing well the blood volume pulsation (BVP), BP can be estimated next via the pulse wave velocity (PWV) theory. Effort is dedicated by this paper to optimize the sizes and geometry of the proposed sensor to maximize the electrode curvature change for largest measured signal-to-noise ratio (SNR) possible, which maximizes the accuracy of BP estimation. To this end, the optimization via the finite element modeling and the Taguchi method is carried out. In results, the optimal sizes in height/radius, fillet, hardness, and the electrode position of the polymer disc are successfully derived, which are in the height of 2 mm, the radius of 6mm, the distance between the planar electrode and the bottom surface of sensor being 1 mm, the hardness of the encapsulating polymer being 25 in shore A hardness, and the fillets at the bottom of the polymer disc being 1 mm in radii. BP is measured for 59 subjects. The resulted errors are 3.60 +/- 5.40 mmHg (mean difference +/- standard deviation) and 1.15 +/- 1.63 mmHg for SBP and DBP, respectively. The correlations are 0.8787 and 0.9648, demonstrating well the favorable performance of the developed sensor.
Robust control design for precision positioning of a generic piezoelectric system with consideration of microscopic hysteresis effects
(2011-06-01)
Chao, Paul C-P
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Liao, Pen-Yen
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Tsai, Meng-Yen
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Lin, Chin-Teng
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影像與生醫光電研究所
This study performs precision positioning of a generic piezoelectric structure against hysteresis effects by finite elements, microscopic hysteresis cancellation and robust H? compensation. The designed control algorithm is expected to be effective in enhancing servo performance of hard disk drives. The precision positioning is accomplished by adding a polarization term into the linear constitutive equations of piezoelectric materials. This polarization term is then described by the well-known Preisach model. Applying basic principles of finite elements and Hamilton's thoery, the macroscopic governing equations of an arbitrary piezoelectric system in finite elements are obtained. Based on the macro-model, a controller consisting of two parts is designed to perform the precision positioning of a generic piezo-structure. The first part is responsible for direct hysteresis cancellation at the microscopic level, while the second one is a robust H(infinity) controller to overcome inevitable cancellation errors. In this way, the control effort is then more effective than the conventional PI and double-lead controller without microscopic hysteresis cancellation. A simple piezoelectric structure of a bender-bimorph cantilever beam is considered for designs and experimental validation. Based on experimental results, the proposed control design is found effective to suppress hysteresis effects as opposed to conventional controllers.