A 10 nW, 10 mV signal detector using a 2 pA standby voltage reference, for always-on sensors and receivers
A 10 nW, 10 mV signal detector using a 2 pA standby voltage reference, for always-on sensors and receivers
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DOI：
10.1109/apec.2018.8341147
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发表时间：
2018-03
期刊：
影响因子：
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通讯作者：
S. Adami;Guang Yang;Chunhong Zhang;P. Proynov;B. Stark
中科院分区：
文献类型：
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作者：
S. Adami;Guang Yang;Chunhong Zhang;P. Proynov;B. Stark
RF能量收集电路通常被设计为最大化效率并因此最大化输出功率，而无源唤醒无线电通常针对高开路输出电压进行优化，从而导致高灵敏度。这两个功能具有相互冲突的设计要求，但通常在物联网设备中都需要。本文提出了一种新的方法来保持几乎整个系统完全断电，同时收听，同时也获得了一个有效的唤醒和能量收集电路使用相同的整流天线（整流天线）。该拓扑结构使用了一个针对效率进行了优化的整流天线，以及两个从电池中汲取高达3.5 nA电流的信号检测器电路。一个检测器被配置为在85 mV触发，以在有足够的功率可用于获得净正能量收集时启动升压转换器。另一个检测器设置为更灵敏，以便在整流天线输出达到10 mV时唤醒子系统。给出了检测器结构和晶体管级设计，并对检测阈值和功率电平进行了实验验证。该电路在10 mV灵敏度下功耗为10 nW，在85 mV灵敏度下功耗为3.9 nW。该检测系统是第一个报告的具有可配置检测阈值的电路，该检测阈值仅从电池汲取nW，并且除了RF信号之外，还可以用于任何瞬态信号，例如来自压电传感器、麦克风或产生超过约10 mV的能量采集器的输出。该电路的低功耗主要归功于UB20M电压检测器的使用，其内部按需基准电压发生器也在这里报告。它具有2 pA的最低待机电流和亚微秒级的开启响应时间。
An RF energy harvesting circuit is usually designed to maximise efficiency and therefore output power, while a passive wake-up radio is usually optimised for a high open-circuit output voltage resulting in high sensitivity. These two functions have conflicting design requirements, but are generally both needed in Internet-of-Things devices. This paper presents a new approach to holding almost the entire system fully powered down whilst listening, whilst also obtaining an effective wake-up and energy harvesting circuit using the same rectenna (rectifying antenna). The topology uses a rectenna that is optimised for efficiency, and two signal detector circuits that draw up to 3.5 nA from the battery. One detector is configured to trigger at 85 mV, to start up the boost converter when enough power is available to obtain netpositive energy harvesting. The other detector is set to be more sensitive, to wake up subsystems when the rectenna output reaches 10 mV. The detector architecture and transistor-level design are presented, and the detection threshold and power levels experimentally verified. The circuit draws 10 nW at a sensitivity of 10 mV, and 3.9 nW at 85 mV. This detection system is the first reported circuit with a configurable detection threshold that draws only nW from the battery, and that, in addition to RF signals, can be used with any transient signals, such as outputs from piezoelectric sensors, microphones, or energy harvesters that produce in excess of around 10 mV. The low power consumption of this circuit is largely due to use of the UB20M voltage detector, whose internal on-demand voltage reference generator is also reported here. It has the lowest reported standby current of 2 pA, and a sub-microsecond-scale turn-on response time.