Study On CMOS Power Amplifiers Design For Radio Frequency Identification Readers

The rapid development of Radio Frequency Identification (RFID) has emerged in multiple domains. A typical RFID system is comprised of reader, tags and computer system. In this paper, study is focused on the power amplifier (PA) technology designed for RFID reader with CMOS process. Based on the realization of a highly-integrated CMOS PA, researches are concentrated on the transmitter RF frontend of reader aiming at different RFID protocols. Meanwhile, a wirless switch system is designed based on the theory of RFID to satisfy the purpose of zero standby energy consumption for household appliance. Also study is spread to power control technology according to the demand of mobile RFID readers.1) The whole course to design a fully-integrated, CMOS class-E power amplifier is implemented, whose inductors in output stage are adopted with bonding wires. And the resonating characteristics of each matching network of PA are expatiated in details. Also a feasible method to improve the matching characteristic is proposed based on the analysis to test results.2) A straightforward, high-efficient RF transmitter frontend is proposed for the demanding of ISO18000-6B protocol. The transmitter is comprised of a RF signal modulator and an output-controllable power amplifier. The 18% modulation depth of RF signal is achieved in signal modulator. And the 100% modulation index is fulfilled inside PA.3) A new structure of transmitter frontend is proposed for the demanding of EPC global Class1 Generation2 protocol. The transmitter is comprised of an active mixer, a linear PA and a non-linear PA. By the alternate action of linear and non-linear PAs, linear ASK modulating data and constant-envelope energy is transmitted to tags.4) Based on the energy-catching technology in RFID tags, a wirless switch system is designed to achieve the purpose of zero standby power consumption for household appliances. The design shemes of the remote controller and the switching circuit in household applicance are described in details. Meanwhile the module of signal modulation and amplification in remoter controller is implemented with CMOS process.5) A feasible power control scheme is designed to satisfy the demand of mobile RFID reader. In the design, two Class-E power amplifiers with different output power are paralleled with their power supply modulated by a class-S modulator. Also a phase-adjustable CMOS phase shifter is added before each PA in order to eliminate the phase mismatch of two paths. A high efficiency above 40% is achieved over an output power range of 18dBm-26dBm. The feasibility of the design is verified.