Study on the Influence Trends of Passive Components on Phase Noise in Crystal Oscillators

Based on the Leeson model, this paper conducts an in-depth study of the impact trends of passive components on phase noise in crystal oscillator circuits. By analyzing the design of a low-phase-noise oscillator using a Pierce-structured capacitive three-point oscillating circuit—including its circuit architecture and equivalent circuit—and deriving an expression for the loaded quality factor (Q<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</inf>) based on a two-port network model, this study reveals the influence rules of key parameters such as the limiting resistor and load capacitance on phase noise. The effectiveness of the Q<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</inf>-based parameter optimization method is also validated. The research results provide systematic theoretical support and engineering implementation pathways for the design of high-precision crystal oscillators.