A Hybrid Pulling Mitigation Synthesizer for NB-IoT Transmitter
This paper presents the pulling mitigation synthesizer integrated with the transmitter for the NB-IoT applications. The proposed synthesizer employs a hybrid phase compensation and sampled filter scheme to mitigate the pulling effects by the transmitter. The pulling mitigation synthesizer is fully integrated with the dual-band NB-IoT transmitter covering 700 MHz – 900 MHz and 1.7 GHz – 2 GHz in the low band and high band respectively. The proposed pulling mitigation improves the EVM by 11.5% with 16 QAM modulation and in single-tone measurements, the achieved pulling suppression is 24 dB. Implemented in 40nm CMOS, the pulling mitigation occupies a small area of 0.18 × 0.18 mm² and the DC power consumption is 1 mW. The measured phase noise of the synthesizer with pulling mitigation is -116.7 dBc/Hz and -115.1 dBc/Hz from 1 MHz offset in the low band and high band respectively.