RF CMOS$LC$-Oscillator With Source Damping Resistors

Abstract

This letter proposes a new method to suppress the 1/ <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$f$</tex> noise contribution of active devices in an oscillator using source damping resistors. The operational mechanism of the proposed source damping resistor method is analyzed through circuit simulation with a complementary <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$LC$</tex> -oscillator. The reduced 1/ <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$f$</tex> noise leads to the phase noise improvement by suppressing 1/ <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$f$</tex> noise up-conversion to phase noise. The measurement result shows that there is about 6.0dBc and 4.0dBc of phase noise improvement at 10kHz and 100kHz offset frequency with differential complementary <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$LC$</tex> -oscillator topology, respectively.