Lu, Ting HengTing HengLuLiu, Chi WeiChi WeiLiuWu, Chuan YiChuan YiWuHuang, Cong ShengCong ShengHuangChen, Jing SiangJing SiangChenChen, Ling ChiaLing ChiaChenHuang, Yao WeiYao WeiHuangOu, I. CheI. CheOuLee, Sook KuanSook KuanLeeChen, Yen ChiYen ChiChenChen, Po HungPo HungChenCHI-TE LIUYING-CHIH LIAOLiao, Yu TeYu TeLiao2023-05-262023-05-262022-12-0119324545https://scholars.lib.ntu.edu.tw/handle/123456789/631401This paper presents an energy-autonomous wireless soil pH and electrical conductance measurement IC powered by soil microbial and photovoltaic energy. The chip integrates highly efficient dual-input, dual-output power management units, sensor readout circuits, a wireless receiver, and a transmitter. The design scavenges ambient energy with a maximal power point tracking mechanism while achieving a peak efficiency of 81.3% and the efficiency is more than 50% over the 0.05-14 mW load range. The sensor readout IC achieves a sensitivity of-8.8 kHz/pH and 6 kHz·m/S, a noise floor of 0.92 x 10-3 pH value, and 1.4 mS/m conductance. To avoid interference, a 433 MHz transceiver incorporates chirp modulation and on-off keying (OOK) modulation for data uplink and downlink communication. The receiver sensitivity is-80 dBm, and the output transmission power is-4 dBm. The uplink data rate is 100 kb/s using burst chirp modulation and gated Class E PA, while the downlink data rate is 10 kb/s with a self-frequency tracking mixer-first receiver.enCMOS | energy harvesting | microbial energy cell | power-efficient | readout IC | soil monitoringjournal article10.1109/TBCAS.2022.3222089363748722-s2.0-85142822670WOS:000966957400001https://api.elsevier.com/content/abstract/scopus_id/85142822670