MTJ based Temperature-Adaptive VCO (TAVCO) for Compensating CP-PLL Frequency Drift

The Charge Pump Phase-Locked Loop (CP-PLL) is a commonly utilized component in contemporary mixed-signal electronic systems. It is widely employed for clock generation, synchronization, and frequency synthesis in both digital and wireless functionalities. However, the frequency accuracy of oscillators can be adversely affected by variations in frequency across a broad temperature range. To address this issue, the voltage-controlled oscillator designed in this study employs a four-stage differential delay structure, chosen for its simple circuit architecture, favorable control linearity, and low noise characteristics. This research integrates the temperature behaviors of Complementary Metal-Oxide-Semiconductor (CMOS) and Magnetic Tunnel Junction (MTJ) technologies, utilizing 28nm CMOS technology to enhance the frequency stability of ring oscillators effectively. Simulation results indicate that frequency drift is reduced by 92% within the temperature range of -80°C to 125°C.