A wirelessly powered low‐power digital temperature sensor

Abstract

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.

A new technique for power transmission and full duplex communication employing SN IPT system

“…The impedance of the secondary coil and reflected impedance to the primary coil are described in Equations ( 4) and (5), respectively.…”

“…In DWC method, the EV batteries are charged through the wireless power transfer technique (WPT) without any need of stopping at a charging station. The applications of wireless power transfer extend from low‐power applications such as medical devices, mobile phones, and so forth to high‐power grid interfaces 3–5 …”

“…The applications of wireless power transfer extend from low-power applications such as medical devices, mobile phones, and so forth to high-power grid interfaces. [3][4][5] The inductive power transfer (IPT) has been the most adopted technique for wireless power transfer since it is reliable and safe. 6 In IPT, the coupled coils system is used to transfer the power from the source to the load.…”

Multiple‐load wireless power transmission system through time‐division multiplexed resonators

“…Several applications have been considered for wireless power transmission (WPT) within last decade including electrical vehicles (EVs), 1,2 wireless charger for consumer electronic devices, 3,4 implantable medical devices (IMDs), 5–7 and drug delivery systems 8 . At the same time, we have observed a rapid growth in use of the tiny sensory devices and actuators which are connected through a network.…”

Characteristic analysis and suppression of SiC MOSFET‐based crosstalk for inductive power transfer systems

“…As an alternative to the conventional charging method, inductive power transfer (IPT) was recently proposed for the batteries charging. IPT can realize the noncontact power supply and eliminate the electrical connection between the power and the load 1–4 . And due to the significant simplification of the charging process, IPT technology brings forward the convenience for the users and could, therefore, be a critical factor for the further popularity of electric vehicles (EVs) 5–8 .…”