FLICKER NOISE IN CMOS LC OSCILLATORS国外硕士论文

qitianhua

A Thesis Presented to The Academic Faculty
By Dale Scott Douglas In Partial Fulfillment Of the Requirements for the Degree
Master of Science in Electrical and Computer Engineering
Georgia Institute of Technology
December, 2008
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+ {/ R& B) f9 GSUMMARY
+ Q  }! F% {6 E& bSources of flicker noise generation in the cross-coupled negative resistance oscillator
(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
others, seeking the mechanisms by which flicker noise is upconverted.
: O# Y; r2 M! Q- C! Q. D3 BA Figure of Merit (FOM) methodology suitable to the 1/f3 phase noise region is also
+ h: q+ j7 x( G" U# p: W9 p8 Cdeveloped, which allows a new quantity, FOM1, to be defined. FOM1 is proportional to
flicker noise upconverted, thus allowing the effectiveness of flicker noise upconversion
5 ?. P% @, F0 S7 tsuppression techniques to be evaluated, despite possibly changing bias points or tank Q,
) X% z1 X* B7 I1 v# S( l0 C7 W9 c" Ewhich 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
& P2 O- ?/ E0 b# [LC CMOS oscillators. A method of adaptive control of an oscillator core is presented, as
well, comprised of a CMOS oscillator with a digitally adjustable N and P width, and a
circuit (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
' H9 Y; T( @4 i" S2 g* K5 K0.7dB of optimal FOM1 for all cases of N width, for a varactorless oscillator test cell.
& J( m% `. W1 I1 L7 e. hFinally, a circuit is proposed which would allow the flicker noise reduction technique
+ g2 t% i" p' E5 a; nof cycling to accumulation to be applied to continuous time oscillators, but is not
6 h) n, M) }8 t& U  R$ v* Srigorously vetted.