دانلود مقاله ترجمه شده افزایش کارایی ترانزیستور حساس به یون اثر میدان (ISFET) با تکنیک مدار بهود یافته – مجله الزویر

فهرست مطالب:

 چکیده
۱ مقدمه
۲ اثر بدن در ISFET
۳ طراحی رابط سنسور
۴ نتایج و بحث
۱ ۴ اندازه گیری ISFETI-V
۲ ۴ تست حساسیت pH
۳ ۴ تست دریفت بلند مدت
۴ ۴ تست وابستگی دما
۵ نتایج

بخشی از ترجمه:

۵٫ نتایج
یک تکنیک ساده برای کاهش اثر بدن کاربردی عمومی و فراگیر در بهبود عملکرد ISFET های مختلف دارد. تنها یک ISFET با خروجی پیکره بندی تفاضلی، راه حل هایی برای مسائل اثر بدن، وابستگی دمایی و دریفت بلند مدت و همچنین جبران نویز مشترک حاصل می کند. ابزارهای مطرح شده با تکنیک اجرا شده کاهش اثر بدن، صحت اندازه گیریهای انجام شده توسط ISFET را بهبود بخشیده و درعین حال عملیات ها را در سطح ولتاژ سورس درین و جریان درین ثابت حفظ می کنند. اجرای طرح مدار پیشنهادی در فرایند یا پروسه CMOS فلز چهار لا و دو لا ۰٫۳۵ TSMC صورت گرفت. به علاوه، مدار جبران خطای آفست dc با ولتاژ کنترل شده سیگنال استخراج شده برای هر سنسور، را به سطح dc مطلوب برای مبدل A/D تعدیل می دهد. این تکنیک مطرح شده برای میکروسیستم های مبتنی بر ISFET یکنواخت مناسب می باشد.

بخشی از مقاله انگلیسی:

۱٫ Introduction The ion sensitive field effect transistor (ISFET), invented in 1970 by Bergveld [1], is a solid-state device that combines the chemically sensitive membrane with the MOS type fieldeffect transistor. In its extensive study over the past 30 years [2–۴], ISFET has been characterized and measured [5,6], indicating drawbacks related to: thermal-dependency, longterm drift and hysteresis. These factors limit the accuracy of ISFET-based measurements systems, especially for biomedical and analytical applications. Another important parameter, the slope of characteristic (sensitivity), also characterize an ISFET. Due to the basic characteristics of ISFET, the potentiometric method has been used to measure the change in pH through ∗ Corresponding author. Tel.: +886 3 2654615; fax: +886 3 2654699. E-mail address: eldanny@cycu.edu.tw (W.-Y. Chung). a corresponding shift in the device threshold voltage. In order to extract the relevant signal from the electrical behavior of the sensor, it is necessary for the ISFET to be accompanied by an analog readout interface [7–۱۲]. Recent works have projected to integrate ISFET and the interface electronics on the same chip [13–۱۷]. Due to the low drift and high mobility properties of carriers, n-channel ISFETs are generally used. In most of today’s CMOS processes, the NMOS device is fabricated into a p-type substrate that is globally and constantly grounded by connection to the most negative supply in the system. Thus, the above-mentioned interface circuits suffer from the problem that the substrate potential greatly influences the device characteristics in ISFET-based integrations. Previous researches [4,5,7,12] show that the constant voltage and constant current (CVCC) biasing technique has been the most widely used method for ISFET sensing. In 2004, Morgenshtein et al. presented a novel technique, which allows body effect elimination of readout interface in CMOS 0925-4005/$ – see front matter © ۲۰۰۵ Elsevier B.V. All rights reserved. doi:10.1016/j.snb.2005.06.018 556 W.-Y. Chung et al. / Sensors and Actuators B 113 (2006) 555–۵۶۲ ISFET-based microsystems [18]. However, in order to keep the constant potential of reference electrode, the direct complementary ISFET/MOSFET pair (CIMP) circuit with gate feedback is not suitable for sensor array readout applications. In addition, indirect CIMP circuit with gate feedback can only have a constant VDS bias but varying drain current. Furthermore, many electronic circuits have been developed to compensate for the thermal-dependence and longterm drift of ISFET. In 1987, Wang et al. described a zero temperature coefficient adjustment and a temperature coeffi- cient (TCF) compensation method to reduce the temperature coefficient of a pH-ISFET [6]. This ‘zero TCF adjustment of the output voltage’ would be suitable in the case of real time control or measurements where the pH value of a solution is within a certain region. However, it is necessary to find the drain current required for each ISFET individually. In 1999, Palan et al. used two identical readout circuits with two ISFETs of different gate materials (Si3N4 and Al2O3), so that these ISFETs of different sensitivity could compensate for temperature-dependency and long-term drift for biomedical applications [8]. However, in this case there is no full verifi- cation of the proposed differential configuration because that the circuit has not been fully tested during pH measurements. In 2003, Casans et al. reported a novel voltage-controlled conditioning circuit applied to the ISFETs temporary drift and thermal-dependency [19] and then in 2004 published a novel electronic compensation in ISFET drawbacks minimization [20]. This compensation method required the expense of extra electronics or miscellaneous numerical calculations. This paper proposes a simple approach enhancing accuracy of measurements by ISFET by using a body-effect reduction technique, while maintaining constant drain-source voltage and current. With a differential configuration of amplifier circuit, this design technique generates an output signal independent of temperature and long-term drift. In addition, a voltage-controlled dc offset error compensation circuit modulates the extracted signal to the desired dc level for the A/D converter for each sensor. Simulation and experimental results demonstrate the effectiveness of the instrumentation system for monolithic ISFET integration in CMOS technology.

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