A 1.6GHz Ultra-Low Phase Noise GaAs HBT PLL for Anti-Radiation Applications

In this letter, a phase-locked loop frequency synthesizer with ultra-low phase noise is proposed in 2-μm GaAs HBT process. To obtain lower phase noise and better start-up condition, a g
_m
-boosted Colpitts VCO is proposed to mitigate the out-band phase noise. Moreover, to reduce the in-band phase noise, GaAs HBT emitter coupled logic PFD and frequency divider were also employed. To validate the proposed idea, a prototype operating at 1.6 GHz is designed, and fabricated. The measured results show that a phase noise of -104.35 dBc/Hz@10kHz and -130.8 dBc/Hz@1MHz with reference spur of -73 dBc are achieved, demonstrating great competitiveness over than other tradition ones. Additionally, due to properly-selected fabrication process, the proposed frequency synthesizer has satisfactory radiation-hardened performance compared with those of the traditional silicon-based circuits. The proposed frequency synthesizer is a potentially ideal candidate for low phase noise and radiation-hardened applications.