A 144-MHz Fully Integrated Resonant Regulating Rectifier With Hybrid Pulse Modulation for mm-Sized Implants

Abstract

This paper presents a fully integrated resonant regulating rectifier (IR3) with an on-chip coil used to wirelessly power mm-sized implants. By combining rectification and regulation in a single stage, and controlling this stage via a hybrid pulse-width modulation and pulse-frequency modulation (PFM) feedback scheme, the IR3 avoids efficiency-limiting cascaded losses while enabling tight voltage regulation with low dropout and ripple. The IR3 is implemented in 0.078 mm2 of active area in 180-nm Silicon oxide insulator (SOI) CMOS, and achieves a 1.87% $\Delta V_{{{\textrm{DD}}}}/V_{{{\textrm{DD}}}}$ power supply regulation ratio with a 1-nF decoupling capacitor despite a tenfold load current variation from 8 to 80 $\mu {{\text{A}}}$ . A 0.8-V $V_{{{\textrm{DD}}}}$ is maintained at a 8- ${{\text{k}}}\Omega $ load for 144-MHz RF inputs ranging from 0.98 to 1.5 V. At 1-V regulation, the voltage conversion efficiency is greater than 92% with less than 5.2- ${{\text{m}}}V_{{{\textrm{pp}}}}$ ripple, while the power conversion efficiency is 54%. The measured overall wireless power transfer system efficiency, from the primary coil to $V_{{{\textrm{DD}}}}$ output of the IR3, is 2% at 160- $\mu {{\text{W}}}$ load, and reaches 5% at 700 $\mu {{\text{W}}}$ .