A 920-MHz, 160-μW, 25-dB Gain Negative Resistance Reflection Amplifier for BPSK Modulation RFID Tag

This paper describes a negative resistance reflection amplifier for BPSK modulation RFID tag. The amplifier has a cascode configuration with a source degeneration capacitor and resistor. The capacitor with 1-bit binary capacitance controlled by a FET switch can realize two different impedances with negative resistance in which those impedance phase difference is close to 180 degrees. The fabricated amplifier using HEMT devices achieves 25 dB gain with the phase difference of $180~\pm ~10$ degrees between reflection coefficient point $\boldsymbol {\varGamma }_{0}$ and $\varGamma _{1}$ for BPSK modulation with a power consumption of $160~\mu $ W. Friis transmission equation suggests that the tag incorporating our amplifier could extend the up-link communication range up to 40m.