Power Management in Wireless Power-Sipping Devices: A Survey

Proper operation of active circuits in a wirelessly powered system requires both sufficient power flow and voltage. Passive (battery-less) wireless systems, operating in the high-frequency band, pose a challenge: generating sufficient amount of supply voltage from very low-input-power flow. The answer to this problem involves implementation of a new class of power-sipping, voltage multiplying power management blocks, which have a wide variety of applications from implantable microelectronic devices (IMD) to internet of things (IoT) and radio-frequency identification (RFID). This paper presents a comprehensive literature survey on the rectification and voltage multiplication of low-input power signals in the frequency range of 100 MH z-1 GH z in remotelypowered systems which require up to several hundred ?A current and operate with less than 3 V supply voltage. The survey covers topologies of voltage multipliers, novel devices, and efficiency/voltage boosting techniques. Since existing voltage multipliers are designed with various process technologies, a comparison among available devices in various topologies is difficult. For a fair comparison between specifications of several state-of-the-art topologies, we have migrated and simulated some of them in one exemplar process technology under the same set of constraints. We observe that the voltage multiplier with cross-coupled configuration yields the best power conversion efficiency at an optimized input voltage; however, it drops immediately after this voltage is reached. We also found that the voltage multiplier with Schottky diodes, used in the Dickson topology, exhibits the lowest sensitivity. When input voltage increases to a level of more than 1 V, the Dickson voltage multiplier with ultra-low-power diodes maintains the highest efficiency, reaching around 80% in the wide input voltage range. To gain a perspective of practical implementation, we also explore various design issues.