A 13.56 MHz RF Frontend with Current-Mode Demodulator for Wide Input-Power Dynamic-Range

This article presents the design of an analog RF frontend for a 13.56 MHz transponder which can operate in a wide range of input powers. The frontend allows wireless telemetric data transmission and also powers the whole system. Implemented in a 0.35 μm CMOS technology the design includes the full-wave rectifier with voltage limiter, low dropout regulators with bandgap reference, a current-mode ASK demodulator supporting modulation indices from 10 to 40 %, clock recovery circuit, and a digital protocol engine. The modulator and demodulator allow the application in ISO 18003 Mode 1 compliant systems. The incident power can range from 460 μW up to 460mW and resistive loads up to 1 kΩ can be applied. The current consumption of the analog frontend itself is only 150 μA and it occupies an area of 0.85 mm² in the chosen CMOS technology.