A kind of uhf RFID reader integrated duplexer on chip

Abstract

The invention belongs to the technical field of semiconductor radio frequency integrated circuits and discloses an on-chip integrated duplexer for a UHF (Ultra High Frequency) RFID (Radio Frequency Identification) reader-writer. The on-chip integrated duplexer comprises a first hybrid transformer, a second hybrid transformer, a first balanced network, a second balanced network and a balun circuit, wherein the center taps of secondary coils of the first hybrid transformer and the second hybrid transformer are respectively connected with the positive output end and the negative output end of a differential power amplifier; the two ends of the secondary coil of the first hybrid transformer are respectively connected with the balanced port of the balun circuit and the first balanced network; the two ends of the secondary coil of the second hybrid transformer are respectively connected with the balanced port of the balun circuit and the second balanced network; the dotted terminal of a primary coil of the first hybrid transformer is connected with the non-dotted terminal of the second hybrid transformer, the dotted terminal of a primary coil of the second hybrid transformer is connected with the non-dotted terminal of the first hybrid transformer, and the two joints are respectively connected with the input end of a frequency mixer; the unbalanced port of the balun circuit is connected with an off-chip antenna of the reader-writer. The on-chip integrated duplexer realizes transmitting-receiving isolation.

Description

technical field [0001] The invention relates to the technical field of semiconductor radio frequency integrated circuits, in particular to an on-chip integrated duplexer of a UHF RFID reader. Background technique [0002] In the process of reading the tag, the UHF RFID reader needs to transmit a continuous carrier wave with sufficient high power to the tag while receiving the signal reflected by the tag for energy supply of the tag. The frequency of the continuous carrier is exactly in the center of the frequency band of the received signal, and the frequency interval from the useful signal is only 40KHz-250KHz. It is difficult to use an RF filter to filter the leakage of the continuous carrier in the received signal. Usually, an off-chip directional coupler is used. To achieve the isolation of transmit and receive paths. Due to the limited isolation of the directional coupler, there will still be a large emission leakage at the input end of the receiver, which will reduce ...

AI Technical Summary

Problems solved by technology

However, the transmitting and receiving signals of UHF RFID are in the same frequency band, so the traditional duplex technology is not suitable for UHF RFID readers

Images