An Asynchronous Analog Self-Powered CMOS Sensor-Data-Logger With a 13.56 MHz RF Programming Interface

Abstract

Design and implementation of a hybrid energy scav- enging integrated circuit (IC) is presented which includes an asyn- chronous self-powered analog se nsor-data-logger (SDL) unit and a 13.56 M Hz radio-frequency (RF) programming interface. The SDL unit operates on an event-bas ed analog self-powering tech- nique where the energy for sensing, computation and non-volatile storage is harvested directly from the signal being sensed. By ex- ploiting operational primitives inherent in a controlled hot-elec- tron injection mechanism, the S DL unit eliminates the need for voltage regulation, energy storage, ADCs, MCUs and RAMs which are commonly used in traditional energy scavenging sensors. Re- mote programming and data interrogation of the SDL unit are per- formed using an integrated 13.56 MHz RF back-telemetry inter- face. The interface consists of a 6- instruction set digital command and control unit based on a token-ring architecture; a high-voltage generator for programming floating-gate (FG) transistors; and an RF front-end unit for communicating with an external reader. We show that the self-powered design is suitable for integration with electro-capacitive transducers (e.g., piezoelectric transducers) that can generate open-load voltages greater than 5 V and drive cur- rents less than 200 nA. Measured results from prototypes fabri- c a t e di na0 . 5 - m standard CMOS process demonstrate that the IC consumes less than 90 nA in the s elf-powering mode and less than 200 W of po