Browsing by Author "Tran, Trong-Hieu"

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A 1.5 mW front-end readout circuit for a small-sized melanin sensor
(2016-06-01)
Cheng, Shih-Song
;
Huang, Sheng-Chieh
;
Tran, Trong-Hieu
;
Shao, Kai-Yu
;
Chao, Paul C. -P.
This study presents a novel readout circuit that serves to evaluate quantity of skin melanin in a noninvasive way via utilizing a photoplethysmography (PPG) optical sensor. PPG sensors are widely used nowadays for noninvasive diagnosis due to their salient features such as low cost and easy-to-useness. PPG signal is known highly correlated with human skin condition and cardiovascular system health. A new readout circuit featuring high-bandwidth, low-noise and low-power is designed in this study to evaluate quantitatively the melanin content of human skin based on PPG signals with high accuracy. This new readout circuit is intended to convert and amplify the electric current of the photo diode in the PPG sensor to voltage signals, and then being further properly amplified to the full dynamic range of the chip circuit fabricated by the TSMC 0.18 mu m process for maximum S/N ratios. The designed circuit has a front-end transimpedance amplifier (TIA), 60 dB in gain, with a degenerate resistor to perform a low noise less than 3 A mu V/aeHz while operating by a 3.3 V supply. In related circuit designs, the mismatch in current sources caused by CMOS process variation is mitigated by a current steering digital-analog-converter (DAC) with least significant bit (LSB) corresponding to 1.25 A mu A. Both TIA and DAC are designed with effort to render high accuracy in the digital outputs for the levels of sensed melanin. The power consumption of chip design is as low as 1.5 mW, while the error rate between measurement and simulation result is less than 3 %.
A 1.5 mW front-end readout circuit for a small-sized melanin sensor
(2016-06)
Cheng, Shih-Song
;
Huang, Sheng-Chieh
;
Tran, Trong-Hieu
;
Shao, Kai-Yu
;
Chao, Paul C. -P.
This study presents a novel readout circuit that serves to evaluate quantity of skin melanin in a noninvasive way via utilizing a photoplethysmography (PPG) optical sensor. PPG sensors are widely used nowadays for noninvasive diagnosis due to their salient features such as low cost and easy-to-useness. PPG signal is known highly correlated with human skin condition and cardiovascular system health. A new readout circuit featuring high-bandwidth, low-noise and low-power is designed in this study to evaluate quantitatively the melanin content of human skin based on PPG signals with high accuracy. This new readout circuit is intended to convert and amplify the electric current of the photo diode in the PPG sensor to voltage signals, and then being further properly amplified to the full dynamic range of the chip circuit fabricated by the TSMC 0.18 mu m process for maximum S/N ratios. The designed circuit has a front-end transimpedance amplifier (TIA), 60 dB in gain, with a degenerate resistor to perform a low noise less than 3 A mu V/aeHz while operating by a 3.3 V supply. In related circuit designs, the mismatch in current sources caused by CMOS process variation is mitigated by a current steering digital-analog-converter (DAC) with least significant bit (LSB) corresponding to 1.25 A mu A. Both TIA and DAC are designed with effort to render high accuracy in the digital outputs for the levels of sensed melanin. The power consumption of chip design is as low as 1.5 mW, while the error rate between measurement and simulation result is less than 3 %.
A 3.2 mW MIXED-SIGNAL READOUT CIRCUIT FOR AN ORGANIC VERTICAL NANO-JUNCTIONS SENSOR
(2016)
Chao, Paul C. -P.
;
Su, Chin-I
;
Tran, Trong-Hieu
;
Zan, Hsiao-Wen
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電子工程學系及電子研究所
A new sensitivity organic vertical nano-junctions (VNJ) sensor for ammonia detection and its readout system are presented in this study. The designed ammonia sensor, VNJ-P3HT diode, is a simple structure with real-time response, high reproducibility and low-cost sensor. Along with the designed sensor, a precision and robust readout circuit is designed and successfully implemented as the proposed chip in this study. To utilize for a novel organic bio-chip, a particular readout system is presented that can acquire signal, compute and display concentration values of ammonia without using microcontroller. The chip is fabricated by the TSMC 0.18-mu m 1P6M 3.3V mixed signal CMOS process technique for verification. Experiment results show that the average resolution is 70.48mV/log(ppm) in a short transient time response, 50 seconds, as compared to prior study, 200 seconds. Error rate, average noise and detection rate reliability are 2.86%, 123 mu Vrms, and 99.6%, respectively. This chip could be suitable for application in cars, cell phones, watches, etc.
A Low-ppm Digitally Controlled Crystal Oscillator Compensated by a New 0.19-mm(2) Time-Domain Temperature Sensor
(2017-01-01)
Tran, Trong-Hieu
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Peng, Hsuan-Wen
;
Chao, Paul C. -P.
;
Hsieh, Jing-Wen
;
電子工程學系及電子研究所
A low-ppm digitally controlled crystal oscillator (DCXO) in a Pierce readout topology with a new 0.19-mm(2) CMOS time-domain temperature sensor (TDTS) circuit for temperature compensation is designed and fabricated in this paper. The Pierce readout circuit is designed to output a 16-MHz oscillating signal as an important base clock for mobile devices. To cope with inevitable imprecision caused by environmental temperature variation, the readout should be compensated based on crystal\'s frequency-temperature curve via a temperature sensor. To this end, a new low-power, small-sized, CMOS on-chip temperature sensor circuit is successfully synthesized by 20-stages of newly designed delay cells. Each delay cell is compensated by a CMOS-process-compatible varactor, enabling a TDTS consisting of only a low number of delay cells to generate long enough delay that is proportional to temperature and in required precisions. In addition to Pierce and TDTS circuits, the DCXO consists of the logics to compute capacitance correction, a switched-capacitor array to adjust Pierce capacitances, and regulators for DCXO and TDTS. The proposed circuits are fabricated by TSMC 0.18-mu m CMOS process, where the active area is 0.516 mm(2) for the whole chip, while 0.19 mm(2) for the TDTS. With temperature compensation enabled, the best measured frequency deviations of a calibrated TCXO is within +/- 0.2 ppm from -40 degrees C to 85 degrees C. The temperature resolution of the developed TDTS is successfully designed to reach 0.18 degrees C/LSB with an accuracy of +/- 1 degrees C validated by one of the tape-out chips.
A new prediction model on the luminance of OLEDs subjected to different reverse biases for alleviating degradation in AMOLED displays
(2015-12-01)
Yu, Ming-Hung
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Tran, Trong-Hieu
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Hsu, Yen-Ping
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Chao, Paul C. -P.
;
Lee, Kuei-Yu
A new prediction model for estimating luminance degradation of an OLED subjected to varied combinations of forward and reverse biases is proposed. To this end, the known increase in the voltage of OLEDs under long-time operation versus degraded emitted luminance is first-time ever considered to identify the degradation exponent as logarithm functions of elapsed time. With the identified degradation versus time, the degraded OLED luminance can be well predicted even subjected to varied combinations of forward and reverse biases. The established model is particularly useful for achieving required lifetime of modern AMOLED displays. Based on the model in terms of equations, the OLED parameters including forward, reverse bias stresses, and initial luminance can be applied to the model to accurately estimate the luminance variation during long-time operation. The estimation error between model predictions and experimental measurements is less than 1.6 %.
A NEW SMALL-SIZED NON-DISPERSIVE INFRARED (NDIR) SENSOR AND ITS DRIVE/READOUT CIRCUITS
(2016)
Chao, Paul C. -P.
;
Hsu, Li-Chi
;
Tran, Trong-Hieu
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A new miniaturized, non-dispersive, infrared (NDIR) sensor for CO2 intended to be installed in mobile phones and its drive/readout circuits are presented in this study. A typical NDIR sensor consists of three main components; an infrared (IR) light emitter (light source), a gas chamber, a photo detector (PD) light receiver) and the associated drive/readout circuits. The geometry of the gas chamber is optimized to minimize the total module . size to approximately 10 mm x 5 mm x 5 mm, which is much smaller than commercially-available gas sensors. Driver and readout circuits are successfully designed and taped out. The driver circuit intends to generate pulse width modulation (PWM) signal to control proper dimming of LED. The readout circuit, which acquires small signal from photo detector then converts to digital values, includes amplifier, low pass filter and analog-to digital converter (ADC). The proposed circuit is fabricated by the TSMC 0.35 mu m CMOS process, where the area is 4.527 mm(2) while power consumption is 60.16 mW for the whole chip. The resolution is less than 12 ppm along with time constant is 0.1 sec.
Design and development of a new wireless fall detection module for homecare
(2015-12-01)
Tran, Trong-Hieu
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Chao, Paul C. -P.
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Hsu, Li-Chi
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Chiu, Chun-Wei
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Kao, Yung-Hua
This study aims to develop a decision procedure and associated small-sized, wearable wireless hardware module for successful fall detections of subjects for homecare. The detection procedure is developed based on a newly-proposed two-level criteria framework. The first-level criterion is forged based on two real-time signal vector magnitudes (SVMs) to determine whether falls can occur. The baseline SVM is further modified to accommodate varied gestures of the subjects prior to fall. It is designed that the modified SVM, named SVMB, with level exceeding 2.5 G indicates that the subject has fallen. The criterion at the second level is developed to prevent false detections, which considers especially the cases that some particular body movements other than falling would induce large SVMB values, such as running. Results based on a number of experimental trials validate the effectiveness of the proposed two-level criterion to detect falls while prevent false detections. A total of 100 experimental falls were tested, an average accuracy rate of 97 % in fall detection is achieved.
Using maximum likelihood to calibrate a six-DOF force/torque sensor
(2018-11-01)
Tran, Trong-Hieu
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Wang, Yu-Jen
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Cheng, Chun-Kai
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Chao, Paul C. -P.
;
Wang, Chun-Chieh
This study presents a new six-DOF force/torque sensor and its calibration method. This calibration method apply the method of so-called maximum likelihood estimation (MLE). MLE is utilized to determine and identify the parameters related to applied torques/forces towards resulted deformations at varied locations of the sensor structure. Formulating such relations in a vector-matrix form, those parameters are captured as coefficients in a matrix related to torques/forces towards angular/linear deformations in different directions. In addition to applying MLE, finite element modeling and analysis are conducted to generate realistic-like empirical data for the afore-mentioned calibration computation. The matrix formed by these coefficients can predict exactly forces and torques by this sensor based on deformations detected by strain gauges. In simulated results the worst sum of error for three forces is less than 0.04% while the worst sum of error for three torques is less than 0.005%. Experiments are also conducted, and the results show that the designed sensor and maximum-likelihood parameter estimation approach achieve favorable performance of predicting forces and torques with error less than 1%. The developed sensor is suitable for real-time sensing of multi-dimensional interactive forces/torques in a robot arm.