Fully Integrated On-Chip Coil in 0.13 <formula formulatype="inline"><tex Notation="TeX">$\mu {\rm m}$</tex></formula> CMOS for Wireless Power Transfer Through Biological Media

Abstract

Delivering milliwatts of wireless power at centimeter distances is advantageous to many existing and emerging biomedical applications. It is highly desirable to fully integrate the receiver on a single chip in standard CMOS with no additional post-processing steps or external components. This paper presents a 2 × 2.18 mm(2) on-chip wireless power transfer (WPT) receiver (Rx) coil fabricated in 0.13 μm CMOS. The WPT system utilizes a 14.5 × 14.5 mm(2) transmitter (Tx) coil that is fabricated on a standard FR4 substrate. The on-chip power harvester demonstrates a peak WPT efficiency of -18.47 dB , -20.96 dB and -20.15 dB at 10 mm of separation through air, bovine muscle and 0.2 molar NaCl, respectively. The achieved efficiency enables the delivery of milliwatts of power to application circuits while staying below safe power density and electromagnetic (EM) exposure limits.

Silicon-Integrated High-Density Electrocortical Interfaces

“…In biological tissues, the tradeoff between coil design and tissue losses results in an optimal frequency for wireless power transmission where efficiency is maximized. For example, the inductance of coils located on miniaturized, millimeter-scale implants ranges from 10 to 100 nH [66], [88], [146], [147]. To compensate for reduced magnetic flux through the miniaturized receiving coil, the carrier frequency for wireless power transfer should be increased, often into the hundreds of megahertz to single-digit gigahertz range [66], [146]- [149].…”

Single chip wireless condition monitoring of power semiconductor modules

“…For this type of sensor, the on-chip coil is a critical component. As demonstrated by von Arx and Najafi, it is possible to achieve good power transfer efficiency from an external reader to a carefully designed on-chip coil [6]. An initial attempt at producing a prototype on-chip coil is demonstrated in this work, and experiments performed on it provides some insight in problems that can arise.…”

Millimeter-scale integrated and wirewound coils for powering implantable neural microsystems

“…To wirelessly power mm-scale IMDs, researchers have proposed several techniques including: ultrasonic, mid-field, and near-field powering [4]- [7]. In particular, ultrasonic links can achieve good power transmission efficiency (PTE) [4], but may not be suitable for powering multiple neural IMDs because of poor skull penetration and high sensitivity to depth/orientation.…”

“…[6]- [10]. For wireless power transmission to mm-scale IMDs, a 2 × 2.18 mm 2 integrated CMOS coil was reported in [7] providing good manufacturability, reliability, and cost competitiveness. On the other hand, a bondwire-based coil wound around an application specific integrated circuit (ASIC) can provide an improved Q-factor and save active silicon area when compared to a fully-integrated system [8], [11].…”

“…Micromachined coils can also improve the Q-factor through: lifting metal traces away from lossy silicon substrates, replacing lossy through-silicon-vias (TSVs) with polymer-enhanced TSVs, electroplating metal traces [9], [10]. Although each fabrication process has its own merits [7], [11], [12], there is still an open debate as to which method is the best for different mm-scale applications.…”