Impulse sensitivity function-based phase noise study for low-power source-coupled CMOS multivibrators

摘要

In this paper, two micropower frequency references implemented with a 0.13- and a 0.25-μm CMOS process for low-power sensor applications are presented. Both circuits are based on a power-optimized source-coupled CMOS multivibrator. The 2.0-MHz frequency reference uses a nominal 1.8–2.5-V supply voltage. The 24.6/307.2-kHz frequency reference is an evolution of the 2.0-MHz reference and operates with a lower supply of 1.0 V and provides two active operating modes. With 1-pF load capacitances, the 2.0-MHz and 24.6/307.2-kHz frequency references typically consume 6.7 μA and 230/750 nA, respectively. After presenting experimental results relating to frequency trimming and frequency stability, this paper concentrates on the phase noise study of the proposed frequency references. The procedure used to apply the impulse sensitivity function-based (ISF) phase noise method to CMOS oscillators is described in detail. The phase noise results of both the implemented references obtained with this method agree well with the measurements. Keywords Impulse sensitivity function - Low-power circuit - Low-voltage circuit - Multivibrator - Oscillator - Phase noise