A wireless power interface for rechargeable battery operated neural recording implants.
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%
Li
Pengfei
P
Dept. of Electr. & Comput. Eng., Florida Univ., Gainesville, FL 32611, USA.
Principe
Jose C
JC
Bashirullah
Rizwan
R
D000669:Amplifiers, Electronic; D011211:Electric Power Supplies; D004560:Electricity; D004567:Electrodes, Implanted; D004581:Electronics; D004582:Electronics, Medical / Q000379:methods*; D004867:Equipment Design; D006801:Humans; D008838:Microcomputers; D008839:Microelectrodes; D008904:Miniaturization; D009474:Neurons / Q000473:pathology*; D019736:Prostheses and Implants; D015203:Reproducibility of Results; D013686:Telemetry