A 2.4-GHz Bluetooth CMOS RF Transceiver with Improved On-Chip TX/RX Matching and Switching Circuit

This paper presents a fully integrated 2.4-GHz Bluetooth radio frequency (RF) transceiver featuring an area-efficient on-chip RF input/output (RFIO) circuit implemented in a 65-nm CMOS process. The proposed single-ended RFIO, sharing a single antenna pin for both T/R paths, eliminates the need for external transmit/receive (T/R) switches and off-chip impedance matching networks. It achieves a highly compact footprint by minimizing the on-chip LC component count to just four. Furthermore, the reconfigurable RFIO inherently provides a sliding-IF image suppression notch in RX mode and a third-harmonic (HD3) attenuation notch in TX mode. A dedicated calibration circuit is incorporated into the class-D power amplifier to optimally minimize second-harmonic (HD2) distortion. Operating from a 1-V supply, the transceiver consumes 4.77 mW in RX mode and 5.92 mW in TX mode. Experimental measurements demonstrate the RX noise figure of 4.82 dB, with a significantly improved image blocker tolerance of −18.9 dBm. The transmitter delivers −0.5 dBm of fundamental output power while achieving an excellent, state-of-the-art HD2 suppression of −66.6 dBc and HD3 suppression of −43.1 dBc. With its minimal silicon area and robust performance, the proposed transceiver provides a highly attractive solution for low-cost and small form factor wireless Bluetooth applications.