Research Of Self-interference Cancellation Technique And Linearization For Receiver And Its Application In UHF RFID

With the rapid development of integrated circuit and communication technology, the wireless devices with a variety of standards have completely penetrated into people’s daily life. The communication between people and things will be inevitably affected by the emission interferences, such as the co-frequency interferences. Moreover, full duplex communication is more attractive for designers to meet the requirement of high data rate, but its co-frequency interference issue between transmitter and receiver is more serious. Due to the co-frequency self-interferences (SI), the design of high performance receiver is difficult. This dissertation focuses on the cancellation of SI and the linearization of RF receiver and makes them applied to ultra-high frequency (UHF) RFID system.The desired signal is probably compressed and distorted by the SI. Based on the principle of analog SI cancellation, the pros and cons of various SI cancellation methods have been analyzed in the dissertation. Thus we find out one method to meet the requirements of this system. Through theoretical analysis and formula derivation, the influence on SI cancellation by amplitude and phase is presented. Finally we discuss that how to effectively optimize and improve the performance of SI cancellation.The performance of the receiver depends on the characteristics of each block. According to the protocol of UHF RFID system, the specifications of RF receiver with the SI have been presented. And the performance of the receiver modules also have been assigned with the receiver cascade analysis. System simulations have been performed to verify the specifications of system with MATLAB Simulink tool.This dissertation proposes a method for 840-960 MHz analog SI cancelltion, and integrates it into UHF RFID receiver. Moreover, a newly encoding to reduce the control bits is presented for the active phase shiner and simplify the digital logic. The simulation results show that it achieves good cancellation performance. The SI suppression ratio is 23～38 dB considering the SI power is 8 dBm. The SI suppression ratio is even greater than 28 dB in the bandwidth of 100 MHz, which is 840～940 MHz.An ultra-low power received signal strength indicator (RSSI) based on the subthreshold biasing is represented in the dissertation. And the power comsuption of the limiting amplifier and the maximum error of the RSSI are also optimized. The RSSI is verified through tape-out in CSMC 0.153μm CMOS process. With a 1.8V supply voltage the overall current consumption is only 6μA. Providing an input dynamically varying -59 dBm to -14 dBm, the measured error is smaller than 1 dB.Receiver with high linearity avoids the deterioration of signal-to-noise ratio from the inter-modulation distortion. Finally after investigating the characteristics and limitations of single capacitive cross-coupling LNA, this dissertation exhibits a double capacitance cross-coupling technique, which significantly improves the nonlinear characteristic of the LNA maintaining broadband matching. IIP3 is enhanced from 4 dBm to 11.5 dBm below 1 GHz. It also reduces noise figure by 0.2 dB in the low frequency band. In addition, against the residual SI and other weak interferences, a UHF receiver with high linear front-end is also put forward. The dc offset generated from 8 dBm SI can be reduced to 14 mV within 100μs for the UHF RFID system, which effectively improves the performance of restraining the SI.