عنوان مقاله
معرفی یکسوسازbulk-driven ولتاژ پائین برای کاربردهای بیومدیکال
فهرست مطالب
چکیده
مقدمه
LV LP WTA بر مبنای تکنیک bulk-driven
یکسوسازLV LP براساس BD WTA
نتایج شبیه سازی
نتیجه گیری
بخشی از مقاله
آمپلی فایر دوم توسطM2, M3, M4, M8, M9, M5 و M10 شکل گرفته است که M2, M3, M4 مرحله ورودی ، M8–M9 بار فعال مرحله اول و M5–M10 دومین مرحله تقویت را نشان می دهند. ترانزیستور M4 که به عنوان سورس جریان دنباله ای عمل می کند به هر دو مرحله ورودی تعلق دارد. همچنین بدیهی به نظر می رسد که هر دو آمپلی فایر داری ترانزیستور مشترک M3 می باشند که به هر دو جفت تفاضلی M1–M3 و M2–M3 تعلق دارد، در حالیکه ولتاژ خروجی به سمت پایانه بالک فیدبک (بازخورد) می شود.
کلمات کلیدی:
Low-voltage bulk-driven rectifier for biomedical applications Fabian Khateb a,n , Spyridon Vlassis b a Department of Microelectronics, Brno University of Technology, Technická 10, Brno, Czech Republic b Electronics Laboratory, Physics Department, University of Patras, Patras 26504, Greece article info Article history: Received 16 November 2012 Received in revised form 15 April 2013 Accepted 22 April 2013 Available online 21 May 2013 Keywords: Low-voltage low-power rectifier Winner-take-all circuit Bulk-driven MOS transistor abstract This paper introduces the novel design of a low-voltage low-power voltage rectifier based on bulk-driven (BD) winner-take-all (WTA) circuit. The proposed circuit is able to work as a half- or full-wave rectifier and it is specifically designed for battery-powered implantable and wearable medical devices. The main attractive features of the proposed circuit are topology simplicity, minimal number of transistors, accuracy and capability of rectifying signals with a relatively wide range of frequencies and amplitudes. The circuit was designed with single voltage supply of 0.6 V and consumes about 2.14 mW. Detailed simulations using TSMC 0.18 mm n-well CMOS technology were performed to prove the functionality and to fully characterize the circuit performance. & 2013 Elsevier Ltd. All rights reserved. 1. Introduction During last decades the specific implementations of analog integrated circuits in the area of biomedical applications have become very attractive [1,2]. Applications such as implantable wearable electronics [3], physiological process monitoring [4], neural recording [5] and medical imaging systems [6] are among the most important. One of the most essential requirements of such circuits is the need of extremely low-voltage (LV) supply, low-power (LP) consumption [1–6] and the small size. Many of the aforementioned applications are portable and require small battery size and lightweight with prolonged lifetime. As the device’s gate oxide thickness and dimensions of state-ofthe-art of CMOS decrease, it results in improvement of the speed and shrinking of the circuits’ area of digital systems, the supply voltage must be decreased for reliability issues [7]. For analog circuits the continuous decreasing of the supply voltage and the relatively high threshold voltages are the main limitations regarding the LV design. The threshold voltage remains at relatively high level compared to the supply voltages in order to minimize the leakages which is one of the main drawbacks in modern processes. Therefore, non-conventional analog design topologies suitable for operation under LV and LP environments must be invented. The voltage rectifier with LV LP capabilities is one of the basic blocks that is necessary in a variety of wearable biomedical electronics systems which are used for real time processing of biological signals [8]. Such biological signal could be generated by bionic implants [9], neural recording systems [10], surface electromyography systems [11] and artificial feedback and management systems [12]. Several LV LP rectifiers for biomedical applications were proposed in the literature [13–18]. The known approach for voltage rectifiers is based on winnertake-all (WTA) circuit, which was firstly presented in [19]. Many WTA circuits were employed in the implementation of currentmode [20] and voltage-mode rectifiers [21,44]. However, these rectifiers are not suitable for biomedical applications since they need extremely LV and LP conditions. Non-conventional design techniques as bulk-driven [22,35], floating-gate and quasi-floating-gate [36–41] were introduced to reduce or even to remove the threshold voltage requirements from the signal path. The bulk-driven technique was first presented in [22] and many low-voltage active building blocks were designed based on this technique, such as voltage followers [23,24], opamps [25,26], operational transconductance amplifiers (OTAs) [27– 31], second generation current conveyor (CCII) [32,35], current differencing external transconductance amplifier (CDeTA) [33] and differential-input buffered and external transconductance ampli- fier (DBeTA) [34]. The main advantage of the aforementioned building blocks is the high input common-mode range since the input signal is applied to the bulk terminal of the input devices [22–35]. The main limitation of the bulk-driven technique is small bulk transconductance which is 3 to 5 times smaller than the corresponding gate-transconductance. Consequently, a relatively large input-referred noise occurred compared to the input-referred noise of gate-driven MOS devices [25,26,34]. Also, due to smaller bulk transconductance and larger input capacitance of the BD
