A design of RF receiving circuit of RFID reader

A design method of the received radio circuit of a radio frequency identification (RFID) reader is introduced, which works in the 915MHz ISM frequency. Because the RFID tag uses back-scattered modulation signal to communicate with reader, and the back-scattered signal much weaker than transmitted signal of the reader, to receive back-scattered signal while transmit is the key problem. To solve it a multichannels receiver is used. It can eliminate blind spot, and improve its sensitivity. A lumped-distributed low-pass filter with high frequency capacitance is present. It rejects unwanted harmonic frequency, and has low insertion loss, small dimension and low cost.