用于超高频射频识别读写器Mixer-First接收机的新型直流分量消除技术

由于收发隔离度有限,超高频射频识别读写器的接收机面临着发射机载波泄漏的问题,基于MixerFirst结构的接收机,提出了一种新型的直流分量消除技术.在无源混频器的中频输出端设计一个由电感、电容等器件组成的带通滤波器,滤除泄漏载波经过下变频产生的直流分量.同时相比于传统的交流耦合方式,该技术可以缩短直流分量的稳定时间.仿真结果表明,当标签返回信号数据率为400kb/s时,该结构的带通滤波器的直流衰减约为-50dB,同时直流分量的稳定时间约为6μs,只有传统交流耦合方式的一半左右.该技术可以扩展接收机的动态范围.

A New DC Cancellation Technique for a Mixer-First Receiver in UHF RFID Reader

The receiver in ultra-high-frequency(UHF) radio frequency identification(RFID) reader suffers from large carrier leakage due to finite TX-to-RX isolation.A new DC cancellation technique for a Mixer-First receiver is proposed in this paper.A bandpass filter composed of an inductor and a capacitor is designed to cancel the large DC component caused by the carrier leakage at the output of the passive mixer.Compared with the conventional AC coupling,the new technique is able to shorten the settling time of the DC component.Simulation results indicate that the attenuation to the DC component is around-50 dB when the data rate of the back-scattered FM0 signal is 400 kb/s.The settling time is around 6 μs and half of that of the conventional AC coupling.The proposed technique can extend the dynamic range of the receiver.