Resonant-Inductive Degeneration for Manifold Improvement of Phase Noise in Bipolar LC-Oscillators

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Resonant-inductive degeneration of bias current source is described in this paper as a method for a manifold improvement of phase noise in inductance–capacitance (<emphasis emphasistype="boldital">LC</emphasis>) voltage- controlled oscillators. For the verification of this phase-noise reduction method, a test bipolar <emphasis emphasistype="boldital">LC</emphasis>-oscillator has been designed using a phase-noise model obtained from the spectral noise analysis. By forming a resonance at twice the oscillation frequency in the emitter of the bias current source transistor, phase noise of the <emphasis emphasistype="boldital">LC</emphasis>-oscillator is improved by 6 dB. Phase noise of <formula formulatype="inline"><tex Notation="TeX">${-}$</tex> </formula>112 dBc/Hz at 1 MHz offset from a 5.7 GHz-band carrier has been realized using oscillator with resonant-inductive degeneration, while drawing 4.8 mA from a 2.2 V supply. The test oscillator achieves a frequency tuning range of 600 MHz, between 5.45–6.05 GHz. </para>