FLICKER NOISE IN CMOS LC OSCILLATORS国外硕士论文

qitianhua

A Thesis Presented to The Academic Faculty
* B% W+ L/ |) e1 O0 v) C0 ]) F6 GBy Dale Scott Douglas In Partial Fulfillment Of the Requirements for the Degree
) d5 a% t/ ^  l7 bMaster of Science in Electrical and Computer Engineering
! h( b( ?9 G; h# P3 MGeorgia Institute of Technology
% Q0 }8 w2 p: L+ m$ yDecember, 2008

& S# q% ^2 E9 `. ^9 l
SUMMARY
" }" I3 H/ ]6 YSources of flicker noise generation in the cross-coupled negative resistance oscillator
7 ^  T, i, K; x(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
9 P1 ^1 R' s5 {+ iothers, 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
developed, which allows a new quantity, FOM1, to be defined. FOM1 is proportional to
flicker noise upconverted, thus allowing the effectiveness of flicker noise upconversion
  V( C5 e* S! r2 a# {$ Vsuppression techniques to be evaluated, despite possibly changing bias points or tank Q,
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
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
( Z8 h+ n4 T& V1 |: Bcircuit (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
1 P" {( y9 G, d$ Kupconversion. A fixed calibration constant is sufficient to allow convergence to within
# J. j* V- Z+ C" e+ q8 J0.7dB of optimal FOM1 for all cases of N width, for a varactorless oscillator test cell.
8 T, b; K" W) D4 ^7 yFinally, a circuit is proposed which would allow the flicker noise reduction technique
of cycling to accumulation to be applied to continuous time oscillators, but is not
rigorously vetted.