Spectral Analysis of Phase Noise in Bipolar LC-Oscillators - Theory, Verification, and Design

Interpretation of phase-noise generating mechanism in oscillators relies on approximate and numerical calculations for analysis, and simulation tools for synthesis. In this paper, a comprehensive, yet intuitive, phase-noise model is derived as a function of oscillator circuit parameters, suiting both analysis and synthesis of oscillators. Contributions of all noise sources to the phase noise of bipolar inductance–capacitance (LC) voltage-controlled oscillators have been determined using spectral noise analysis. For the verification of the phase-noise model, a bipolar LC-oscillator has been designed that realizes a phase noise of 106 dBc/Hz at 1 MHz offset from a 5.7 GHz-band carrier while drawing 4.8 mA from a 2.2 V supply. The results obtained from the phase-noise model agree well with simulation and measurement results of the LC-oscillator designed.