A 6-bit 360° active phase shifter based on UHF RFID application

Abstract

The invention discloses a 6-bit 360° active phase shifter based on UHF RFID application. Its quadrature signal generating circuit consists of two stages of resistors and capacitors, and converts input signals into quadrature I and Q The signal is then input to the I-channel and Q-channel Gilbert units respectively; the quadrant selector controls the generation of the required phase in the corresponding quadrant, and the coordinate axis selector controls the conversion of the coordinate axis variables when the signal is synthesized in the corresponding quadrant, and then Simplify the logic coding circuit; the current bias array includes I and Q current bias arrays, and the switch control signals are complementary, respectively controlling the amplitude of the I and Q output signals and changing the phase of the synthesized signal; the logic coding circuit mainly Generate the quadrant and coordinate axis selector and the control signal of the current bias array; the adder realizes the vector superposition of the I and Q signals, and outputs a series of signals with the same amplitude and different phases. The invention reduces the chip area, lowers the cost and simplifies the logic coding circuit of the phase shifter.

Description

technical field [0001] The invention belongs to the technical field of active phase shifters, in particular to a 6-bit 360° active phase shifter. The invention is especially applied to the UHF RFID reader system. Background technique [0002] The UHF RFID system is a passive half-duplex identification system. The transmitter of the reader generates and transmits the carrier signal and modulation signal to the outside. The passive radio frequency tag receives the carrier signal and converts it into energy for power supply. The modulated signal backscatters back to the receiving end of the reader. According to the EPC second-generation protocol, in each RFID system communication, the reader must transmit a carrier signal to provide energy for passive radio frequency tags when receiving scattered signals. The characteristic that the transmitter and receiver of the reader-writer work at the same frequency makes the isolation between the receiver and the transmitter very diffic...

AI Technical Summary

Problems solved by technology

Compared with the low-frequency quadrant selector on the DC path, the design of a high-frequency quadrant selector may have many problems, such as noise, phase flatness in the frequency band, parasitic capacitance, etc.

The quadrature signal generation circuit of the phase shifter also adopts RLC structure, which occupies a relatively large area; the encoding circuit method is similar to reference [1], and the logic circuit is also relatively complicated

[0006] Existing active phase shifters are based on control quadrant selection and current bias array to achieve phase tuning, and there is no relevant literature report on coordinate axis selection

Images