Li Pengfei, Principe Jose C, Bashirullah Rizwan
Dept. of Electr. & Comput. Eng., Florida Univ., Gainesville, FL 32611, USA.
Conf Proc IEEE Eng Med Biol Soc. 2006;2006:6253-6. doi: 10.1109/IEMBS.2006.260775.
This paper describes an integrated analog front-end for wireless powering and recharging of miniature Li-ion batteries used in implantable neural recording microsystems. DC signal extraction from a wireless carrier is accomplished using Schottky barrier contact diodes with lower forward voltage drop for improved efficiency. The battery charger employs a new control loop that relaxes comparator resolution requirements, provides simultaneous operation of constant-current and constant-voltage loops, and eliminates the external current sense resistor from the charging path. The accuracy of the end-of-charge detection is primarily determined by the voltage drop across matched resistors and current-sources and the offset voltage of the sense comparator. Experimental results in 0.6 mum bulk CMOS technology indicate that +/- 1.3% (or +/-20 microA) end-of-charge accuracy can be obtained under worst-case conditions for a comparator offset voltage of +/-5mV. The circuits occupy 1.735 mm(2) with a power dissipation of 8.4 mW when delivering a load current of 1.5 mA at 4.1 V (or 6.15 mW) for an efficiency of 73%
本文介绍了一种用于为植入式神经记录微系统中使用的微型锂离子电池进行无线供电和充电的集成模拟前端。利用具有较低正向压降的肖特基势垒接触二极管从无线载波中提取直流信号，以提高效率。该电池充电器采用了一种新的控制回路，放宽了比较器分辨率要求，实现了恒流和恒压回路的同时运行，并消除了充电路径中的外部电流检测电阻。充电结束检测的精度主要由匹配电阻和电流源两端的电压降以及检测比较器的失调电压决定。采用0.6μm体硅CMOS工艺的实验结果表明，在比较器失调电压为±5mV的最坏情况下，充电结束精度可达±1.3%（或±20μA）。当在4.1V下提供1.5mA的负载电流时（或6.15mW），电路占用面积为1.735mm²，功耗为8.4mW，效率为73%
