JSSC 2012第4期RF & Wireless0.25μm CMOSBuck ConverterEnergy Harvesting

A Battery-Free 217 nW Static Control Power Buck Converter for Wireless RF Energy Harvesting With -Calibrated Dynamic On/Off Time and Adaptive Phase Lead Control Tzu-Chi Huang, Student Member , IEEE, Chun-Y u Hsieh, Y ao-Yi Y ang, Student Member , IEEE, Yu - H u e i L e e, Student Member , IEEE,Y u - C h a i K a n g ,K e - H o r n g C h e n, Senior Member , IEEE, Chen-Chih Huang, Ying-Hsi Lin, and Ming-Wei Lee

一款无电池、静态功耗217nW的降压转换器，适用于无线射频能量收集。

95%峰值效率，217nW静态功耗，0.1mV/mA负载调节

无电池降压转换器射频能量收集动态开关时间控制自适应相位领先

▸创新点1：动态开关时间控制(DOOT) - 该方法创新通过预测不同输入电压下的开关时间，无需传统的高功耗零电流检测(ZCD)电路，显著降低了静态功耗（217 nW），同时实现了宽负载范围内的高转换效率（峰值95%）。

▸创新点2：自适应相位领先(APL)机制 - 该电路创新针对低功耗和非理想比较器固有的传播延迟问题，通过动态调整相位领先量，改善了负载调节性能（最大提升30 mV），增强了系统稳定性。

▸创新点3：无电池纳米级降压转换器架构 - 该系统创新整合DOOT和APL技术，专为射频能量采集设计，在0.25μm CMOS工艺下实现0.39mm²芯片面积，具备0.1 mV/mA的优异负载调节能力，解决了能量收集系统中电压波动的适配问题。

▸创新点4：PVT鲁棒性校准方案 - 该辅助创新通过工艺-电压-温度(PVT)变化下的自动校准，确保DOOT控制中零电流检测的准确性，进一步提升了转换效率的可靠性（覆盖全工作条件）。

Abstract

A battery-free nano-power buck converter with a pro- posed dynamic on/off time (DOOT) control can achieve high con- version ef ﬁciency over a wide load range. The DOOT control can predict the on/off time at different input voltages without a power consuming zero current det ection (ZCD) circuit, as well as sup- press static power in idle periods. To adapt to the ﬂuctuations in a harvesting system, the proposed -calibration scheme guaran- tees accurate ZCD over pr ocess, voltage variation, and tempera- ture (PVT) in the DOOT to improve power conversion ef ﬁciency. Furthermore, the adaptive phase lead (APL) mechanism can im- prove inherent propag ation delay attributable to low-power and non-ideal comparator, thus improving load regulation by a max- imum of 30 mV. The test chip was implemented in 0.25- mC M O S process with a die a r e ao f0 . 3 9m m. Experimental results showed 95% peak efﬁciency, low static power of 217 nW and good load reg- ulation of 0.1 mV/mA, which are suitable for RF energy harvesting applications.