J. Craninckx et M. Steyaert, LOW-NOISE VOLTAGE-CONTROLLED OSCILLATORS USING ENHANCED LC-TANKS, IEEE transactions on circuits and systems. 2, Analog and digital signal processing, 42(12), 1995, pp. 794-804
Frequency synthesizers used in modern telecommunication systems, such
as cellular telephones, need to have very low phase noise, Therefore,
in the design of high performance frequency synthesizers using Phase L
ocked Loops (PLL), the Voltage-Controlled Oscillator (VCO) has become
a key issue, The trend towards monolithic integration poses some major
challenges, This paper discusses the phase noise aspects of LC-tuned
oscillators, A general formula is developed, based on the concepts of
effective resistance and capacitance, The formula also applies for osc
illators using active inductors, From these results the importance of
an inductor,vith very low series resistance is apparent. To circumvent
the technological limits given by an inductor's series resistance, a
presented enhanced LC-tank can be used to make a trade-off between noi
se and power.