Wireless power charger for wearable medical devices with in‐band communication

Summary In this paper, a buck‐boost converter circuit for wireless power transfer via inductive links in bio‐implantable systems is presented. The idea is based on reusing the power receiver coil to design a regulator. This method employs five switches to utilize the coil inductor in a frequency other than the power‐receiving signal frequency. Reusing the coil inductor decreases the on‐chip regulator area and makes it suitable for bio‐implants. Furthermore, in the proposed technique, the regulator efficiency becomes almost independent of the coil receiving voltage amplitude. The proposed concept is employed in a buck‐boost regulator, and simulation results are provided. For a 10 MHz received signal with the amplitude variation within 3 ~ 6 V and with the converter switching rate of 200 kHz, the achieved maximum efficiency is 78%. The proposed regulator can also deliver 10 μA to 4 mA to its load while its output voltage varies from 0.6 to 2.3 V. Simulations of the proposed converter are performed in Cadence‐Spectre using TSMC 0.18 μm CMOS technology. Copyright © 2017 John Wiley & Sons, Ltd.

Section: Proposed Inductor-reused Buck-boost Convertermentioning

confidence: 99%

“…For this, the steady state sinusoidal response of current, i s,r (t), should be considered. From Figure 5 and relation (5), it can be written as follows:…”

Section: Design Procedures Of the Proposed Convertermentioning

confidence: 99%

A power efficient buck‐boost converter by reusing the coil inductor for wireless bio‐implants

Barati

Yavari

2017

“…The enormous increase in wireless signal bandwidths, their ranges, and improvements in their power efficiencies have seen a parallel increase in their application in existing and in entirely new scenarios. However, the requirement of a wired power connection considerably curtails the applicability of electronic systems in certain applications where wired power link is just not feasible such as biomedical implants or autonomous wireless sensor systems . This is where wireless power transfer (WPT) has gradually become a necessity.…”

Section: Introductionmentioning

confidence: 99%

A wirelessly powered low‐power digital temperature sensor

Amin

Shahbaz

Jawed

et al. 2020

Summary A wirelessly powered temperature sensor is presented in complementary metal‐oxide‐semiconductor (CMOS) 180‐nm process. The wireless power transfer (WPT) is performed using resonant magnetic coupling, and a diode‐less AC to DC conversion is achieved through a quadrature‐oscillator with native‐MOS. The quadrature‐signals are subsequently used to control the diode‐less rectifier switches. The on‐chip temperature sensor exploits the subthreshold region temperature, and the sensed temperature is converted to frequency using a ring‐oscillator, which is implemented using differential cross coupled oscillator‐based delay cells. The temperature sensor architecture also employs a temperature‐insensitive replica circuit to minimize process dependence and enhance power‐supply rejection ratio (PSRR) of the sensing process. The application‐specific integrated circuit has been designed and fabricated in 180‐nm CMOS process and has dimensions of 2 mm × 2 mm. The measurement results demonstrate that the WPT circuit generates a DC voltage of 1V with a power transfer efficiency of 85% for distances 2 to 8 mm with settling time of microseconds to milliseconds. The temperature sensor demonstrates a resolution of < ±0.6C with a sensitivity of 0.52 mV/C and 126.9 Hz/C along with PSRR of −63dB and Integral Non‐Linraity (INL) of 5% measured across six different dies. The back‐scattering communication demonstrates a −53‐dB signal at a distance of 4 mm without affecting the WPT efficiency. The total power consumption of the temperature sensor along with the integrated biases is 120 nW.

“…[1][2][3][4][5][6][7][8] Different from traditional energy transfer, WPT has a promising future in a wide range of applications as it is able to deliver electrical energy wirelessly without direct cable connections. In recent years, wireless power transfer (WPT) has aroused a great deal of attention.…”

Section: Introductionmentioning

confidence: 99%

Design and optimization of hybrid resonant loops for efficient wireless power transfer

Shi

Gao

Shen

et al. 2017

Frequency splitting, caused by magnetic overcoupling, is a great challenge in resonant wireless power transfer, which leads to decrease of transfer efficiency. In this paper, to avoid the frequency splitting, a new design of hybrid resonant loops with an inner coil positioned in the transmitter is proposed for efficient power transfer. It is shown to suppress dramatic variation of mutual inductance when the distance between transmitter and receiver decreases.Analytical expressions of the mutual inductance and the transfer efficiency for the proposed resonant wireless power transfer system are calculated. To obtain a relatively uniform mutual inductance with respect to the distance, the proposed resonant loops are optimized. Simulation and experiments are also performed to validate the effectiveness of the proposed resonant loops in eliminating the frequency splitting. The transfer efficiency remains higher than 80% when the transfer distance decreases below a critical value where frequency splitting occurs for conventional resonant loops. Furthermore, lateral and angular misalignments between the resonant loops are also considered and investigated. The results indicate that the proposed resonant loops are also applicable in suppressing the frequency splitting even in case of misalignments.KEYWORDS frequency splitting, hybrid resonant loops, mutual inductance, transfer efficiency, wireless power transfer (WPT)