• Journal of Sensor Science and Technology
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• v.32 no.6
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• pp.432-440
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• 2023

This study introduces an efficient readout circuit designed for two-electrode electrocardiogram (ECG) recording, characterized by its low-noise and low-power consumption attributes. Unlike its three-electrode counterpart, the two-electrode ECG is susceptible to common-mode interference (CMI), causing signal distortion. To counter this, the proposed circuit integrates a common-mode charge pump (CMCP) with a window comparator, allowing for a CMI tolerance of up to 20 V_PP. The CMCP design prevents the activation of electrostatic discharge (ESD) diodes and becomes operational only when CMI surpasses the predetermined range set by the window comparator. This ensures power efficiency and minimizes intermodulation distortion (IMD) arising from switching noise. To maintain ECG signal accuracy, the circuit employs a chopper-stabilized instrumentation amplifier (IA) for low-noise attributes, and to achieve high input impedance, it incorporates a floating high-pass filter (HPF) and a current-feedback instrumentation amplifier (CFIA). This comprehensive design integrates various components, including a QRS peak detector and serial peripheral interface (SPI), into a single 0.18-㎛ CMOS chip occupying 0.54 mm². Experimental evaluations showed a 0.59 µV_RMS noise level within a 1-100 Hz bandwidth and a power draw of 23.83 µW at 1.8 V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.7-8
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• 2009

In the presence of infrared light, a CMOS Readout IC (ROIC) for a microbolometer typed infrared sensor detects the voltage or current that is caused by the changing in resistance in the bolometer sensor. A serious problem in designing the ROIC is how the value of the bolometer and reference resistors vary because of variations in manufacturing process. Since different pixel have different, resistance values, sensor operations must contend with fixed pattern noise (FPN) problems. In this paper, we propose a novel technique to compensate for the fluctuation in reference resistance by tiling into account the process variation. By using constant current source basing and correlated double sampling, we solved FPN.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.2
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• pp.119-122
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• 2009

As infrared light radiates, the CMOS Readout IC (ROIC) for the microbolometer typed infrared sensor detects voltage or current which is caused by the variation of resistance in the bolometer sensor. A serious problem we may have in designing the ROIC is the value of bolometer and reference resistors will be changed due to process variation. Since each pixel does not have the same value of resistance, fixed pattern noise problems happen during the sensor operations. In this paper, we propose a novel technique to compensate the fluctuation of reference resistance with taking account of process variation. By using a comparator and a cross coupled latch, we will make the value of reference resistor same as the bolometer's.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.10
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• pp.2359-2368
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• 2013

In this paper, an IRD (internal read data) circuit preventing the reentry into the read mode while keeping the read-out DOUT datum at power-up even if noise such as glitches occurs at signal ports such as an input signal port RD (read) when a power IC is on, is proposed. Also, a pulsed WL (word line) driving method is used to prevent a DC current of several tens of micro amperes from flowing into the read transistor of a differential paired eFuse OTP cell. Thus, reliability is secured by preventing non-blown eFuse links from being blown by the EM (electro-migration). Furthermore, a compared output between a programmed datum and a read-out datum is outputted to the PFb (pass fail bar) pin while performing a sensing margin test with a variable pull-up load in consideration of resistance variation of a programmed eFuse in the program-verify-read mode. The layout size of the 8-bit eFuse OTP IP with a $0.18{\mu}m$ process is $189.625{\mu}m{\times}138.850{\mu}m(=0.0263mm^2)$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.5
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• pp.387-391
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• 2011

A uncooled infrared ray sensor used in an infrared thermal imaging detector has many advantages. But because the uncooled infrared ray sensor is made by MEMS (micro-electro-mechanical system) process variation of offset is large. In this paper, to solve process variation of offset a ROIC for uncooled infrared ray sensor that has process variation of offset compensation technique using differential delta sampling and reference signal compensation circuit was proposed. As a result of simulation that uses the proposed ROIC, it was possible to acquire compensated output characteristics without process variation of offsets.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.223-223
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• 2011

적외선 감지기로 사용되는 microbolometer 소자재료로 VOx 또는 비정질 Si이 가장 많이 사용된다. 그 중에서 VOx 물질은 온도저항계수 즉, TCR이 높고 감지도가 우수하기 때문에 비냉각 적외선 검출기에 많이 응용된다. Microbolometer 검출기는 그 응답도는 micromachining 공정에 의해 좌우되는 열 고립구조에 의해 좌우된다. 특히 TCR 값이 크고, 열시상수 값이 작을수록 양질의 감지도를 얻을 수 있으므로 재료의 선택 및 공정이 매우 중요하다. 따라서 본 연구에서는 비냉각 적외선 감지소자로 사용되는 VOx 박막을 DC Sputtering을 사용하여 증착하였으며, 그 특성을 조사하였다. MEMS 공정에 의한 센서의 제작은 적외선을 흡수하여 저항변화를 읽어내어 판독하는 Readout IC(ROIC) 위에 행해진다. Monolithic 공정에 의해 이러한 ROIC 위에서 공정이 동시에 행해지므로 공정온도는 매우 중요한 요소로 작용한다. 따라서 증착된 VOx 박막의 열처리 효과를 연구하였다. 열처리 온도는 $250^{\circ}{\sim}420^{\circ}C$, 열처리 시간은 20~80 min 까지 변화시켰다. 갓 증착된 VOx 박막의 저항은 약 200 $k{\Omega}$이였으며, TCR은 -1.5%/$^{\circ}C$로 나타났다. 열처리 온도가 증가함에 따라 TCR 값은 증가하였으며, 열처리 시간이 증가할수록 역시 TCR 값이 증가하는 경향을 보였다. 열처리 온도 320$^{\circ}C$, 열처리 시간 40 min에서 TCR 값은 약 -2%/$^{\circ}C$의 값을 얻을 수 있었다. 이러한 성능의 VOx 박막을 이용하여 비냉각형 microbolometer 검출소자를 열변형없이 공정을 수행할 수 있을 것으로 기대한다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.148-149
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• 2008

As infrared light is radiated, the CMOS Readout IC (ROIC) for the microbolometer type infrared sensor detects voltage or current when the resistance value in the bolometer sensor varies. One of the serious problems in designing the ROIC is that resistances in the bolometer and reference resistor have process variation. This means that each pixel does not have the same resistance, causing serious fixed pattern noise problems in sensor operations. In this paper, Reference resistor compensation technique was proposed. This technique is to compensate the reference resistance considering the process variation, and it has the same reference resistance value as a bolometer cell resistance by using a comparator and a cross coupled latch.