طراحی و شبیه‌سازی یک تراشه 8 کاناله با توان مصرفی و سطح تراشه کم برای ارتباط با سیستم عصبی

نوع مقاله : علمی-پژوهشی

نویسندگان

1 دانشکده مهندسی برق - دانشگاه تربیت دبیر شهید رجایی

2 دانشکده مهندسی برق- دانشگاه صنعتی خواجه نصیرالدین طوسی

چکیده

محوریت این مقاله، طراحی یک تراشه 8 کاناله در تکنولوژی µm18/0 TSMC برای ارتباط با سیستم عصبی است که عمل ثبت و تحریک را به‌طور مجزا انجام می‌دهد. تقویت‌کننده سیگنال عصبی ارائه‌شده، مبتنی‌بر تکنیک فیدبک غیرمستقیم با قابلیت برنامه‌پذیری بهره ولتاژ، فرکانس قطع بالا و پایین بوده که با اتصال خازن کوچکی به خروجی آن، می‌توان به فرکانس قطع بالای موردنظر دست‌یافت. همچنین با استفاده از مدار تضعیف‌کننده در مسیر فیدبک، علاوه‌بر افزایش امپدانس ورودی، میزان خازن‌های موردنیاز در مدار نیز کاهش یافته‌است. سطح اشغالی 8 کانال تقویت‌کننده طراحی‌شده برابر با mm227/0 بوده، توان مصرفی هر کانال با منبع تغذیه V8/1 برابر با µW27 می‌باشد و با سوئینگ ولتاژ خروجی Vpp 95/0، مقدار THD برابر با kHz1dB@50- به‌دست آمده‌است. در پایانه تحریک ارائه‌شده نیز علاوه‌بر امکان تولید سیگنال‌های مربعی، امکان تولید سیگنال‌های نمایی با قابلیت برنامه‌پذیری ثابت زمانی، وجود دارد. طبقه خروجی این پایانه تحریک، شامل یک مدار ناقل جریان کلاس B برای انتقال جریان تحریک به بافت هدف در محدوده µA±96 به‌همراه مدارهای تزریق بار برای تأمین ولتاژهای V±3/3 موردنیاز، می‌باشد. مساحت یک کانال تحریک بدون مدارهای پمپ بار برابر با mm2043/0 می‌باشد و براساس شبیه‌سازی‌های انجام‌شده، هنگامی که این پایانه تحریک به مقاومت kΩ25 متصل می‌شود، با توان مصرفی حداکثر mW2/1، ویژگی‌های خواسته‌شده از آن را برآورده می‌شود.

کلیدواژه‌ها


عنوان مقاله [English]

Design and Simulation of a 8-Channel, Low-Power, and Small Chip-Area Neural Interfacing Chip

نویسندگان [English]

  • M. H Maghami 1
  • A. M Sodagar 2
1 Faculty of Electrical Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran
2 Electrical Engineering Department, K. N. Toosi University of Technology, Tehran, Iran
چکیده [English]

This article reports on the design of a 8-channel neural recording amplifier and stimulation back-end in TSMC 0.18µm technology which can do the recording and stimulating simultaneously. The design of proposed neural amplifier is based on indirect negative feedback and provides tunable lower cutoff frequency, and digitally-programmable upper cutoff frequency and voltage gain. Moreover, the proposed circuit employs attenuators in the same feedback loop in order to further reduce the silicon area consumed by the capacitors and at the same time to increase the input impedance of the circuit. The 8-channel designed circuit consumes 0.27mm2 of chip area and operated with a supply voltage of 1.8V, power consumption of each channel is 27µW with the THD of -50dB@1kHz and output voltage swing of 0.95Vpp < /sub>. The designed stimulation bak-end circuit, in addition to traditional rectangular pulse shapes, can generates biphasic stimulation pulses with exponential shapes, whose time constants are digitally programmable. A class-B second generation current conveyor is designed to be used for delivering stimulation current pulses of up to ±96µA to the target tissue and a charge pump block is in charge of the generating supply voltages of ±3.3V. The circuit consumes 0.043mm2 of silicon area for each channel (excluding charge pumps). Simulation results indicate that the stimuli generator meets expected requirements with the maximum power consumption of 1.2mW when connected to electrode-tissue impedance of as high as 25kΩ.

کلیدواژه‌ها [English]

  • Stimulation back-end
  • exponential current stimulation
  • indirect negative feedback
  • neural recording amplifiers
  • current conveyor circuits
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