An On-Chip Configurable Receiver With >55-dB Tx Leakage Suppression for UHF RFID Reader

Abstract

Ultrahigh-frequency (UHF) radio frequency identification (RFID) reader suffers from large Tx leakage due to insufficient Tx-to-Rx isolation, especially for single-chip integration. An on-chip receiver with high Tx leakage suppression (TLS) is proposed. The frequency-translated impedance property of the passive mixer is utilized to transfer the baseband impedance to RF input to form a high-Q impedance matching network. By careful design of the impedance of baseband circuits, at the RF input, the equivalent impedance at the carrier frequency is very low, while the impedance in signal band matches the source. A digital-controlled feedback with configurable bandwidth is introduced to achieve a fast settling process and small attenuation of the signal. The design was implemented with 130-nm CMOS technology. Measured results show that the proposed receiver achieves 55–73-dB on-chip TLS ratio, and the minimum settling time is $1.2~\mu \text{s}$ . The RF front-end noise figure (NF) is less than 18 dB.