Browsing by Author "Chen, Hung-Kai"

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A 0.4V 53dB SNDR 250 MS/s Time-Based CT Delta Sigma Analog to Digital Converter
(2015-01-01)
Chen, Hung-Kai
;
Chen, Wei-Zen
;
Ren Zhiyuan
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper presents the design of an ultra-low voltage (ULV), time-based, continuous-time Delta Sigma analog-to-digital data converter. By replacing the 2nd stage integrator with frequency-calibrated voltage bootstrapping VCO, it circumvents ULV design challenges while achieving a signal bandwidth up to 2 MHz. Back-gate adder, voltage amplifier, and bootstrapping logic cells are also proposed to enable 250 MHz sampling rate operation. The measured peak SNDR is 53 dB under a supply voltage of 0.4 V. The whole ADC consumes 526 mu W. Fabricated in a 90 nm CMOS process, the core area is 0.08 mm(2).
Energy-Effective Sub-Threshold Interconnect Design Using High-Boosting Predrivers
(2012-06-01)
Ho, Yingchieh
;
Chen, Hung-Kai
;
Su, Chauchin
;
電機工程學系
;
電控工程研究所
This paper investigates the performance of the interconnects with repeater insertion in the subthreshold region. A 3X complementary metal-oxide-semiconductor (CMOS) predriver and a 4X one are proposed to enhance the driving capability. As compared to the conventional repeater, the proposed ones have higher energy efficiency. In addition, the results of Monte Carlo analysis indicate that the propose predrivers have higher concentration under the process and temperature variation than conventional one at 0.15 V. A test chip with 3X and 4X predrivers for 10-mm on-chip bus has been fabricated in 65 nm SPRVT CMOS process. The measured results show that the 3X (4X) predrivers can achieve 5 Mb/s (1.5 Mb/s) data rate at 0.15 V with an efficiency of 35.2 fJ (32.8 fJ).
Energy-Effective Sub-Threshold Interconnect Design Using High-Boosting Predrivers
(2012-06-01)
Ho, Yingchieh
;
Chen, Hung-Kai
;
Su, Chauchin
;
電子工程學系及電子研究所
;
電控工程研究所
This paper investigates the performance of the interconnects with repeater insertion in the subthreshold region. A 3X complementary metal-oxide-semiconductor (CMOS) predriver and a 4X one are proposed to enhance the driving capability. As compared to the conventional repeater, the proposed ones have higher energy efficiency. In addition, the results of Monte Carlo analysis indicate that the propose predrivers have higher concentration under the process and temperature variation than conventional one at 0.15 V. A test chip with 3X and 4X predrivers for 10-mm on-chip bus has been fabricated in 65 nm SPRVT CMOS process. The measured results show that the 3X (4X) predrivers can achieve 5 Mb/s (1.5 Mb/s) data rate at 0.15 V with an efficiency of 35.2 fJ (32.8 fJ).
Methodological considerations in calculating heart rate variability based on wearable device heart rate samples
(2018-11-01)
Chen, Hung-Kai
;
Hu, Yu-Feng
;
Lin, Shien-Fong
;
交大名義發表
;
電機工程學系
Heart rate variability (HRV) analysis has recently been incorporated into wearable device application. The data source of HRV is the time series of heart beat intervals extracted from electrocardiogram or photoplethysmogram. These intervals are non-uniformly sampled signals and not suitable for spectral HRV analysis, which usually uses uniformly resampled heart beat intervals before calculating the spectral domain parameters. Such a practice is not applicable to heart rate data obtained from wearable devices that usually display and export the beat per minute (BPM) time series data at 1 Hz. The preferred resampling rate to calculate spectral domain parameters is 4 Hz. We compare the spectral HRV results with the 1 Hz and 4 Hz resampling rates in order to validate the use of 1 Hz resampled-RRI data to represent wearable devices BPM time series data for HRV analysis. Our results show that, using a specific combination of signal processing techniques, the lowest mean relative error in spectral domain parameters of normalized low-frequency power (LFnu), normalized high-frequency power (HFnu) and the ratio of normalized low-frequency power to normalized high-frequency power (LFnu/HFnu) between 1 Hz and 4 Hz are 3.7%, 15.3% and 16.4%, respectively. We conclude that using the heart rate data sampled at 1 Hz produces a reasonable estimation of sympathetic activity but a poor estimation of parasympathetic activity.