A Fully Integrated Pulling Mitigation Synthesizer for NB-IoT Transmitter

This article presents the pulling mitigation scheme implemented in the frequency synthesizer integrated with the dual-band narrowband-internet-of-things (NB-IoT) transmitter (TX). The proposed pulling mitigation in the synthesizer employs a hybrid phase compensation and sampled filter to mitigate the pulling effects by the transmitter. The synthesizer covers frequencies from 700–900 MHz and 1.7–2 GHz in the low band and high band, respectively, satisfying the dual-band NB-IoT frequency tuning specifications. The proposed pulling mitigation in the synthesizer improves the error vector magnitude (EVM) by 11.5% with 16 quadrature amplitude modulation (QAM) modulation and in single-tone measurements, the achieved pulling suppression is 24 dB. Implemented in 40 nm CMOS, the pulling mitigation occupies a small area of $0.18\times0.18$ mm2 and the dc power consumption is 1 mW with a supply voltage of 1.1 V.