RFID system in CMOS technology

Radio Frequency Identification (RFID) system has been widely used for object tracking, inventory managements and security purposes. However, the high volume use of RFID applications is still limited mainly because of the relatively high price of a single RFID tag. In addition, to facilitate the use of RFID system, the RFID reader needs to be integrated with other portable devices particularly cellular handset. Due to its high integration capability and relatively low cost, CMOS technology is one of the best candidates to integrate both RFID reader and tag. Additionally, CMOS technology highly supports digitally controlled circuits and therefore, is suitable for software control multistandard applications.; There are several issues in the design of the RFID system in CMOS. The power generating part of the passive RFID tag suffers from the inefficiency of the diode connected MOSFET transistors. In addition, the use of off-chip antenna in existing RFID system substantially increases the tag's cost and also determines the major portion its physical size. There are also challenges in design of the CMOS power amplifier in terms of its maximum output power as well as power efficiency. This mandates using an off-chip PA for the TX path of the RFID reader which increases the cost overhead of the system. The desirable solution, however, is to provide a high power reconfigurable CMOS PA that supports both cellular and RFID transceivers and also can be integrated with the rest of the circuits.; This dissertation provides a variety of solutions for integration of the RFID system in CMOS technology. This includes the integration of both near field and far field RFID tags in standard CMOS process using an impedance transformation technique to improve the efficiency of the power generating block. In addition, it provides a solution to integrate the tag's antenna on-chip for applications that require a very low cost and secure communication at short range. The proposed RFID system employs a near field communication at UHF band, which enables the integration of the tag's coil on-chip. Moreover, a multimode CMOS power amplifier is proposed which is capable to support near field/far field RFID transmitter as well as cellular applications. The proposed PA can be used in polar transmitter architecture and employs an amplitude modulation scheme based on controlling the bias current. The PA provides a very high power control dynamic range as well as wide bandwidth of amplitude modulation capability. The detailed analysis of the proposed circuits has been explained in detailed that addressing the issues of the CMOS RFID system. The full set of measurement results of the fabricated test circuits has been also presented which support the theory and analysis.