Differentiating ASK Demodulator for Contactless Smart Cards Supporting VHBR

Abstract

This paper proposes an ASK demodulator that uses switched-capacitor differentiators to make it compliant with the VHBR amendment to the ISO/IEC 14443 standard for contactless smart card applications. These differentiators detect transitions in modulated ASK signals with a carrier frequency of 13.56MHz at data-rates up to 6.78Mbps. The demodulator has been implemented in 0.18μm CMOS technology. The total power consumption is under 350μW. Measured results confirm correct operation, and it is further shown that this differentiating scheme allows the modulation index to be reduced to 2.56%.

Wireless energy‐harvesting circuit and system with error‐correction ASK demodulator for body sensor network with ultra‐high‐frequency RFID healthcare system

“…The desired 925 MHz is concerned by the transmission distance in short range, the ISM band, and the antenna size which will dominate mostly the device size. Moreover, a used standard EPC Class-1 Gen-2 is beneficial to communicate between a RFID reader and a tag on the commercial [10], (c) Differentiating ASK demodulator [11], (d) Differentiating ASK demodulator with transistor only [12] applications. As shown in Fig.…”

“…The circuit is implemented in standard complementary metal–oxide–semiconductor (CMOS) digital technique without any passive component for bioimplantable systems. Lee et al [11] proposed the differentiating ASK demodulator with an envelope detector, a source follower, three stages of differentiators and comparators, moreover an off‐chip rectifier is adopted in front of the ASK demodulator. Gong et al [12] proposed the fully transistor ASK demodulator without any capacitor or resistor.…”

VLSI Implementation of Area and Power Efficient Digital Control Circuit for HF RFID Tag Chip

“…Several former researches about the implementation of ASK demodulator can be found in Refs. [13][14][15][16]], yet we have another method to realize ASK demodulator with very low modulation index (2.33%) and without sacrificing power and area. Once vdd, por, clk, din100 and din10 are all ready, then the digital control circuit starts to work and generate an output coding signal 'dout' for the load modulator.…”

Ultra‐low power current mode all‐ MOS ASK demodulator for radio frequency identification applications

“…However, these works are not efficient in terms of power consumption. Recent works have tried to save more power and area and/or to increase the ratio of data rate to carrier frequency by fully digital implementation [15], down‐converting to the baseband using near‐threshold mixer [16], or by clock extraction and switched‐capacitor differentiators [17]. The current‐mode ASKDs presented in [18, 19] detect the rising and falling edges of the incoming envelope signal using a current edge detector.…”