Browsing by Author "Cheng, Kevin"

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99.4% Peak Audio Signal Recovery Rate and Ultra-Low 0.32dB Matching Error with 10Hz High Resolution Filter Fitting Wearable Aided Speech Compensation System
(2015)
Lin, Yen-Ting
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Lai, Shin-Chi
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Chen, Shin-Hao
;
Peng, Shen-Yu
;
Chen, Ke-Horng
to get high sound quality, the proposed adaptive speech compensation (ASC) system fits psychoacoustic curves for individual needs. Moreover, characteristics of the speakers are considered by real-time speaker impedance estimation (RT-SIE) technique. Hence, original signal can be restored for every user with any speakers. ASC system has 99.4% peak original signal recovery rate by predicting and controlling output signal precisely. And the built-in 10Hz high resolution acoustic filter fitting scheme (AFFS) has less than 0.32dB matching error with an over 80dB hearing loss.
A 2.5W Tablet Speaker Delivering 3.2W Pseudo High Power by Psychoacoustic Model Based Adaptive Power Management System
(2014)
Chen, Shin-Hao
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Peng, Shen-Yu
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Chen, Ke-Horng
;
Lai, Shin-Chi
;
Kang, Sheng
for a 2.5W speaker in tablets, the proposed adaptive power management (APM) system can deliver a pseudo high power of 3.2W with a +/- 4V supply because it suppresses 0.7W power on tones that may damage a 2.5W speaker and escape the notice of human ears. With z-domain digital signal processing (z-DSP) and psychoacoustic model, high efficient power management and high sound quality can be achieved simultaneously. Conventional automatic gain control (AGC) only has the ability of 0.32W power suppression. Moreover, suppressing power by conventional clipping technique increases total-harmonic-distortion (THD). In contrast, the proposed real-time dynamic loading impedance (RT-DLI) monitoring brings forward a way to solve the problem on speaker damage while keeping low THD during high sound pressure level (SPL). THD in the APM system is slightly higher than that of original sound 1.1dB, comparing to the disadvantage of 8.6dB increasing caused by conventional clipping technique.
A Class-D Amplifier Powered by Embedded Single-Inductor Bipolar-Output Power Module with Low Common Noise and Dynamic Voltage Boosting Technique
(2014-01-01)
Chen, Shin-Hao
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Lin, Kuei-Liang
;
Ng, Shao Siang
;
Chen, Ke-Horng
;
Wey, Chin-Long
This paper proposes a high efficiency Class-D amplifier (CDA) with embedded single-inductor bipolar output (SIBO) power module. The characteristics of SIBO converter\'s bipolar outputs not only suppress equivalent common mode noise but also remove several large external bulky components in conventional boost supply CDA systems. Since bipolar outputs in the SIBO provide independent driving capability, CDA is capable of operating in both single-ended (SE) and bridge-tide load (BTL) configurations. Furthermore, the proposed dynamic voltage boosting (DVB) technique adjusts the SIBO output voltage level according to the CDA\'s output level with 5% power efficiency improvement. Peak total harmonic distortion plus noise (THD+N) performance is 0.012%. Peak power efficiency of SIBO and CDA are 89% and 93.2%, respectively.
Dynamic ink-jet printing analysis system with addressable waveform trimming
(2007-01-01)
Huang, Chieh-Yi
;
Shang, Kuo-Chiang
;
Wu, Kuo-Hua
;
Lee, Jeng-Han
;
Liu, Tsu-Min
Definitely the ink jet fabrication is an expectable technology for the fields of display and semiconductors, such like for the fabrication of color filters, the forming of metal circuits, the dispensing of liquid crystal, and for the further continuous manufacture of flexible displays etc. Recently, inkjet printing technologies have been rapidly developing and are not only for the diminished size of the drops to the pico-liter, the multiplex driving scheme, or for the real-time observation technology which led to the improvement of the inkjet printing performance, and which realized the pixel-to-pixel control. In this article, an electrical controller is designed to differentiate the waveform for each nozzle synchronously, to compensate for the nozzle cell deformation and pressure drag loss during inkjet firing at high voltage, and for a high frequency named addressable waveform trimming circuit (AWTC). The controller is composed of a high voltage control block which drives each nozzle, an FPGA chip to multiplex the high voltage output, an AID converter which transfers an analog signal into a digital signal and then into FPGA, a differential signal input to FPGA as feedback to correct analog output, which gives a real-time tracking of jetting quality to verify the nozzle-to-nozzle variation. For dynamic feedback of the drop variation in real jetting, this AWTC accepts correction signals by a machine vision system synchronously with the firing trigger in order to analyze the individual captured images. The maximum support nozzle channel is up to 1280 and can be handled within a 2% jetting accuracy.
Improved performance in n-channel organic thin film transistors by nanoscale interface modification
(2008-04-01)
Chu, Chih-Wei
;
Sung, Chao-Feng
;
Lee, Yuh-Zheng
;
Cheng, Kevin
;
光電工程學系
We demonstrate that the electrical properties of n-channel thin film transistors can be enhanced by inserting a nanoscale interfacial layer, namely, cesium carbonate (Cs2CO3) between organic semiconductor and source/drain electrodes. Devices with the Cs2CO3/Al electrode showed a reduction of contact resistance, not only with respect to Al, but also compared to Ca. The improvement is attributed to the reduction in the energy barrier of electron injection and the prevention of unfavorable chemical interaction between the organic layer and the metal electrode. High field-effect mobility of 0.045 cm (2)/V s and on/off current ratios of 10(6) were obtained in the [6,6]-phenyl C60 butyric acid methyl ester-based organic thin film transistors using the Cs2CO3/Al electrodes at a gate bias of 40 V. (c) 2007 Elsevier B.V. All rights reserved.
Ring edge in film morphology: Benefit or obstacle for ink jet fabrication of organic thin film transistors
(2007-09-01)
Lu, Jhih-Ping
;
Chen, Ying-pin
;
Lee, Yuh-Zheng
;
Cheng, Kevin
;
Chen, Fang-Chung
In this study, a novel process using ink jet printing with dilute PMMA [poly(methylmethactylate)] solution to form fine separation banks as confined boundaries for the subsequent depositing poly(3,4-ethylene dioxythiophene) (PEDOT) was proposed. The PEDOT comprised the source and drained electrodes with a gap of several micrometers due to the innate characteristic of the ring edge of ink jetted PMMA. Using this technique, the organic device was designed with a bottom gate and evaporated pentacene as the channel material. The device mobility and onloff ratio were about 3.6x 10(-4) and 2x 10(2) cm(2) /Vsec, respectively. (C) 2007 Society for Imaging Science and Technology.