A Novel LNTA-first Carrier Leakage Suppression Receiver Front-End with Low Noise Figure and High Sensitivity for UHF RFID Reader

A novel on-chip carrier leakage suppression receiver front-end with low noise figure and high sensitivity for ultrahigh-frequency (UHF) radio frequency identification (RFID) reader is proposed exploring a low-noise transconductance amplifier (LNTA)-first architecture. A 4-path passive mixer and a LNTA are adopted to transfer the baseband band-pass property to the mixer and receiver input and form a band-stop input impedance. As a result, the obvious impedance and gain difference between in-band and carrier signal is the key to achieving leakage suppression. Furthermore, the gain of the LNTA can effectively minimize the noise contribution from subsequent stages of the receiver to reduce noise figure and improve sensitivity. Implemented in a 55nm CMOS process, the noise figure of the LNTA-first receiver front-end is 15.7dB at the offset frequency of 600kHz, which is 4.2dB lower than the mixer-first, so the sensitivity is improved. Furthermore, the carrier leakage rejection ratio is 51dB, which is 1.5dB higher than the mixer-first. The results indicate that the LNTA-first receiver is more promising than the mixer-first in NF and sensitivity without sacrificing leakage suppression for UHF RFID applications.