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 mu m 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 mu W up to 460mW and resistive loads up to 1 k Omega can be applied. The current consumption of the analog frontend itself is only 150 mu A and it occupies an area of 0.85 mm(2) in the chosen CMOS technology.