FLICKER NOISE IN CMOS LC OSCILLATORS国外硕士论文

qitianhua

A Thesis Presented to The Academic Faculty
5 P# ~) m% g. q' r# ABy Dale Scott Douglas In Partial Fulfillment Of the Requirements for the Degree
8 d: V$ N5 @5 o- I7 e6 hMaster of Science in Electrical and Computer Engineering
Georgia Institute of Technology
December, 2008

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6 Z  V( D9 z+ G. w$ k  U8 |+ KSUMMARY
Sources of flicker noise generation in the cross-coupled negative resistance oscillator
5 s0 Q* c% k# J; Z(NMOS, PMOS, and CMOS) are explored. Also, prior and current work in the area of
phase noise modeling is reviewed, including the work of Leeson, Hajimiri, Hegazi, and
& a; w/ n5 l8 z& Eothers, seeking the mechanisms by which flicker noise is upconverted.
A Figure of Merit (FOM) methodology suitable to the 1/f3 phase noise region is also
6 }+ s* y$ x- Y7 r" @developed, which allows a new quantity, FOM1, to be defined. FOM1 is proportional to
5 Q& K: t% }- p7 jflicker noise upconverted, thus allowing the effectiveness of flicker noise upconversion
suppression techniques to be evaluated, despite possibly changing bias points or tank Q,
0 K3 O" g9 p% G2 s$ \+ K! }which would change phase noise and FOM in the 1/f2 region.
The work of Hajimiri is extended with a simple ΛDC estimator for the special case of
' N" S- Y2 i5 h4 Q& QLC CMOS oscillators. A method of adaptive control of an oscillator core is presented, as
- R- a) c3 v1 U& M3 |well, comprised of a CMOS oscillator with a digitally adjustable N and P width, and a
' o. _4 b* s/ n1 E6 ]$ Kcircuit (which is essentially a tracking ADC) which repeatedly adjusts the relative N to P
width dependent on the ΛDC estimate to maintain the condition of minimum flicker noise
upconversion. A fixed calibration constant is sufficient to allow convergence to within
' ~& I1 o# w. A  e5 j/ a2 y0.7dB of optimal FOM1 for all cases of N width, for a varactorless oscillator test cell.
Finally, a circuit is proposed which would allow the flicker noise reduction technique
- J% Y  }# A1 Q, T& m% Dof cycling to accumulation to be applied to continuous time oscillators, but is not
rigorously vetted.