Phase noise optimization of frequency synthesizers using harmonics of reference signal

This paper develops a novel frequency synthesizer using harmonics of the reference signal for the low power consumption and low phase noise requirements of advanced wireless systems. The innovation of our frequency synthesizer is developing an adaptive pulser whose output pulse-width is designed to decrease as the reference frequency increase for enhancing frequency synthesis range. The pulsed reference signal is then mixing with the signal from the voltage-controlled oscillator (VCO). It eliminates the use of high power consumption programmable divider during the steady state. This work have implemented a 2.4 ∼ 2.6 GHz low noise frequency synthesizer using the 0.18µm CMOS technology. Comparing with the conventional synthesizer, the proposed synthesizer improves the in-band phase noise and power consumption by about 16 dB and and 21 mW, respectively.