• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.483-485
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• 2010

A 200kS/s 10-bit successive approximation(SA) ADC with a rail-to-rail input range is proposed. The proposed SA ADC consists of DAC, comparator, and successive approximation register(SAR) logic. The folded-type capacitor DAC with the boosted NMOS switches is used to reduce the power consumption and chip area. Also, the time-domain comparator which uses a fully differential voltage-to-time converter improves the PSRR and CMRR. The SAR logic uses the flip-flop with a half valid window, it results in the reduction of the power consumption and chip area. The proposed SA ADC is designed by using a $0.18{\mu}m$ CMOS process with 1V supply.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.1
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• pp.90-97
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• 2019

The charge redistribution digital-to-analog converter(CR-DAC) is often used for successive approximation register analog-to-digital converter(SAR ADC) that requiring low power consumption and small circuit area. However, CR-DAC is required 2 to the power of N unit capacitors to generate reference voltage for successive approximation of the N-bit SAR ADC, and many unit capacitors occupy large circuit area and consume more power. In order to improve this problem, this paper proposes SAR ADC using series capacitor DAC. The series capacitor DAC is required 2(1+N) unit capacitors to generate reference voltage for successive approximation and charges only two capacitors of the reference generation block. Because of these structural characteristics, the SAR ADC using series capacitor DAC can reduce the power consumption and circuit area. Proposed SAR ADC was designed in CMOS 180nm process, and at 1.8V supply voltage and 500kS/s sampling rate, proposed 6-bit SAR ADC have signal-to-noise and distortion ratio(SNDR) of 36.49dB, effective number of bits(ENOB) of 5.77-bit, power consumption of 294uW.

• Journal of IKEEE
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• v.22 no.4
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• pp.1218-1221
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• 2018

This paper presents a low-power 0.6-V 10-bit 200-kS/s double rail-to-rail successive approximation register (SAR) analog-to-digital converter (ADC). The proposed scheme allows input signal with 4 times power which is compared with conventional one by applying proposed rail-to-rail scheme, and that improves signal-to-noise ratio(SNR) of NTV SAR ADCs. The prototype was designed using 65-nm CMOS technology. At a 0.6-V supply and $2.4-V_{pp}$ (differential) and 200-kS/s, the ADC achieves an SNDR of 59.87 dB and consumes 364.5-nW. The ADC core occupies an active area of only $84{\times}100{\mu}m^2$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.88-90
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• 2012

This paper describes a 10-bit 10-MS/s asynchronous successive approximation register (SAR) analog-to-digital converter (ADC) with a rail-to-rail input range. The proposed SAR ADC consists of a capacitor digital-analog converter (DAC), a SAR logic and a comparator. To reduce the frequency of an external clock, the internal clock which is asynchronously generated by the SAR logic and the comparator is used. The time-domain comparator with a offset calibration technique is used to achieve a high resolution. To reduce the power consumption and area, a split capacitor-based differential DAC is used. The designed asynchronous SAR ADC is fabricated by using a 0.18 um CMOS process, and the active area is $420{\times}140{\mu}m^2$. It consumes the power of 0.818 mW with a 1.8 V supply and the FoM is 91.8 fJ/conversion-step.

• Journal of Sensor Science and Technology
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• v.27 no.1
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• pp.31-35
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• 2018

This paper describes a low-power, SNDR (signal-to-noise and distortion ration) enhanced SAR (successive approximation register) type 12b ADC (analog-to-digital converter) with noise shaping technique. For low power consumption and small chip size of the DAC (digital-to-analog converter), the top plate sampling technique and the dummy capacitor switching technique are used to implement 12b operation with a 10b capacitor array in DAC. Noise shaping technique is applied to improve the SNDR by reducing the errors from the mismatching of DAC capacitor arrays, the errors caused by attenuation capacitor and the errors from the comparator noise. The proposed SAR ADC is designed with a $0.18{\mu}m$ CMOS process. The simulation results show that the SNDR of the SAR ADC without the noise shaping technique is 71 dB and that of the SAR ADC with the noise shaping technique is 84 dB. We can achieve the 13 dB improvement in SNDR with this noise shaping technique. The power consumption is $73.8{\mu}W$ and the FoM (figure-of-merit) is 5.2fJ/conversion-step.

• Journal of IKEEE
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• v.22 no.2
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• pp.514-517
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• 2018

In sensor systems, ADC (analog-to-digital converter) demands high resolution, low power consumption, and high signal bandwidth. Sigma-delta ADC achieves high resolution by high order structure and high over-sampling ratio, but it suffers from high power consumption and low signal bandwidth. SAR (successive-approximation-register) ADC achieves low power consumption, but there is a limitation to achieve high resolution due to process mismatch. This paper surveys architecture improvement of ADC to overcome these problems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.12
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• pp.2317-2325
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• 2016

This paper presents a 10 bit successive approximation register (SAR) analog-to-digital converter (ADC) with a reference driver. The proposed SAR ADC consists of a capacitive digital-to-analog converter (CDAC), a comparator, a SAR logic, and a reference driver which improves the immunity to the power supply noise. The reference driver generates the reference voltages of 0.45 V and 1.35 V for the SAR ADC with an input voltage range of ${\pm}0.9V$. The SAR ADC is implemented using a $0.18-{\mu}m$ CMOS technology with a 1.8-V supply. The proposed SAR ADC including the reference driver almost maintains an input voltage range to be ${\pm}0.9V$ although the variation of supply voltage is +/- 200 mV. It consumes 5.32 mW at a sampling rate of 10 MS/s. The measured ENOB, DNL, and INL of the ADC are 9.11 bit, +0.60/-0.74 LSB, and +0.69/-0.65 LSB, respectively.

• Journal of Semiconductor Engineering
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• v.2 no.1
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• pp.99-108
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• 2021

Successive Approximation Register (SAR) Analog-to-Digital Converters (ADC) seem to become the hottest ADC architecture during the past decade in implementing energy-efficient high performance ADCs. In this overview, we will review what kind of circuit techniques and architectural advances have contributed to place the SAR ADC architecture at its current position, beginning from a single SAR ADC and moving to various hybrid architectures. At the end of this overview, a recently reported compact and high-speed SAR-Flash ADC is introduced as one design example of SAR-based hybrid ADC architecture.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.1
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• pp.129-134
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• 2014

This paper presents a 10-bit 10-MS/s asynchronous successive approximation register (SAR) analog-to-digital converter (ADC) which consists of a digital-to-analog converter (DAC), a SAR logic, and a comparator. The designed asynchronous SAR ADC with a rail-to-rail input range uses a binary weighted DAC using metal-oxide-metal (MOM) capacitor to improve sampling rate. The proposed 10-bit 10-MS/s asynchronous SAR ADC is fabricated using a 0.18-${\mu}m$ CMOS process and its active area is $0.103mm^2$. The power consumption is 0.37 mW when the voltage of supply is 1.1 V. The measured SNDR are 54.19 dB and 51.59 dB at the analog input frequency of 101.12 kHz and 5.12 MHz, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.2
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• pp.414-422
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• 2013

This paper describes a 10-bit 10-MS/s asynchronous successive approximation register (SAR) analog-to-digital converter (ADC) using a split-capacitor-based differential digital-to-analog converter (DAC). SAR logic and comparator are asynchronously operated to increase the sampling frequency. The time-domain comparator with an offset calibration technique is used to achieve a high resolution. The proposed 10-bit 10-MS/s asynchronous SAR ADC with the area of $140{\times}420{\mu}m^2$ is fabricated using a 0.18-${\mu}m$ CMOS process. Its power consumption is 1.19 mW at 1.8 V supply. The measured SNDR is 49.95 dB for the analog input frequency of 101 kHz. The DNL and INL are +0.57/-0.67 and +1.73/-1.58, respectively.