Research And Design Of Wireless Power Management Chip

With the more deeply research of the implantable medical chip,there has been a breakthrough for low-noise amplifier in biological signal frequency band、low-noise low-power analog digital converter and other processing modular.In addition to those fields,another important topic is transmission and processing of wireless power,which is to solve operational difficulties from battery replacement and cable transmission.It takes power of wireless electromagnetic waves by antenna,then converted them to DC power and achieved the sustainable work of the chip.In this article,the related blocks of wireless power management chip are researched and designed.Designing a chip with highly integration and perfect system function and achieving the transmission and management of power is to provide high performance supply voltage to load.This paper introduces wireless power management chip containing charge pump rectifier、bandgap voltage reference、low dropout linear regulator.As the research and design of REC,the paper analyzes an equivalent circuit between the chip and the antenna and comes to conclusion that there is a tradeoff between the signal swing and bandwidth of input.Then,by using the law of conservation of charges,the design flow of REC is summarized and a high efficiency rectifier based on native MOSFET is realized.As the research and design of BGR,the paper analyzes an improved structure based on MOSFET working in sub-threshold region and BJT,then proposes the key factor to determine the stability of process and relevant measures to improve the power supply rejection ratio.As the research and design of LDO,this paper analyzes the working principle of LDO and switch regulator and introduces assistant circuits commonly used in LDO such as shutdown circuit、over-voltage protection circuit、over-current protection circuit、over-temperature protection circuit.Each block of the chip implemented in SMIC 0.18μm is designed and verified in this paper.Post-layout simulation results show that the rectifier efficiency of the REC reaches 60%.650 nA quiescent current is consumed and process stability is at 1% for Improved BGR.The BGR achieves the power supply rejection is-60 dB at DC,-50 dB at 500 MHz.The quiescent current of LDO is 5μA and its efficiency is 66.7% when the maximum load current is 15μA.The power supply rejection is-100 dB at DC,-50 dB at 500 MHz in the case of no-load while The power supply rejection is-55 dB at DC,-50 d B at 500 MHz in the case of full-load.Besides,when the temperature exceeds 70℃ or the load current exceeds 30μA or the input voltage is more than 2.2V,the circuit could be shutdown and achieves self-protection.The Simulation results show,the wireless power management chip designed based on above three blocks,corresponding to different input voltage,achieves a low-noise low-ripple output while the input voltage of LDO can be limited to the safe working region in 1.8V-2V and its output ripple is reduced to 1%.Meantime,while the chip temperature exceeds 70℃ or load current exceeds 30μA,the chip can be shut-down for protection.