Albert Missoni

HF RFID transponder with phase demodulator for very high bit-rates up to 13.56 Mbit/s

Sending larger data volumes over an air interface requires high transmission rates and a demodulator to recognize this data. Amplitude demodulators have been used in the past to detect data rates up to 848 kbit/s and phase demodulators have been used to achieve data rates of 424 kbit/s. This paper presents a 13.56MHz HF transponder with a phase demodulator for very high bit-rates based on the passive near field coupling. The integrated phase demodulator detects phase modulated signals with a bit-rate up to 13.56 Mbit/s at an operating range of 4 cm. On the transponder chip a complete RFID analog front end is integrated. It includes a typical common HF-RFID antenna, for high data rates optimized shunt, phase demodulator and load modulator. A novel phase demodulator principle is introduced in this paper. It uses phase-locked loop (PLL) to obtain accurate time reference for the phase detectors. This allows recognizing the phase shift by the comparison of the incoming phase modulated data with the phase of the time reference. The phase demodulator reported in this paper uses two phase detectors working in an alternating mode. This solution allows to recognize phase shifts of the received data from the antenna with double data rate compared to the solution with one phase detector. The demodulator has been implemented in a 90nm Flash CMOS technology with a supply voltage of 1.5V and a power consumption of 0.56mW. Measurement results show that the phase demodulator is able to recognize very small phase changes down to 5 degrees at a bit rate of 13.56 Mbit/s.

A hybrid voltage reference

In this paper a new voltage reference circuit concept is introduced. The presented voltage reference circuit is especially useful for low power applications. The reference circuit has two modes: the high accuracy and the low power mode. During the high accuracy mode the energy consumption is much higher than during the low power mode where accuracy is secondary. The fields of application are use cases where different specifications are required at different points in time. As an example a lot of chips in mobile devices switch between operational and sleep modes. During operational mode high accuracy is needed. Afterwards, when the chip is in sleep mode for a long time, the current consumption has to be at a minimum.

A Dual Frequency Band Comprehensive RFID TAG

Passive RFID applications are in place in several ISM frequency bands. The three most important bands are: LF (100–135 kHz), HF (13.56 MHz) and UHF (860–960 MHz). Which band is selected depends on the application, on the national radio regulations, on the established RFID infrastructure in this segment or on costs. This work proposes a passive RFID analog front end which operates at two RFID frequency bands. For contactless communication the EPC Gen2 UHF and the EPC HF standard have been implemented. For this purpose a novel single port power generation unit which comprises one wideband rectifier and two low voltage DC/DC converters has been designed. A low power and low voltage local oscillator unit and a new concept for contactless communication including ultra low power circuits for modulation and demodulation are presented. The test chip has been manufactured in a low cost 120 nm Infineon process with EEPROM technology.