FLICKER NOISE IN CMOS LC OSCILLATORS国外硕士论文

qitianhua

A Thesis Presented to The Academic Faculty
- g  k4 c, f; |; Y" bBy Dale Scott Douglas In Partial Fulfillment Of the Requirements for the Degree
. l# t/ F; I! ]* XMaster of Science in Electrical and Computer Engineering
3 _$ {* }- A0 G9 FGeorgia Institute of Technology
December, 2008


9 \) m+ _# I( cSUMMARY
2 Q1 D& R* ]0 w4 [Sources 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
7 [$ ?9 v  k- P% K8 X+ Aphase noise modeling is reviewed, including the work of Leeson, Hajimiri, Hegazi, and
# }1 t" u+ J1 Z  D2 Tothers, 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
2 \7 t. ]# o# p: f6 D) N  ~( qflicker noise upconverted, thus allowing the effectiveness of flicker noise upconversion
, y1 O6 k" A0 E; K  e! Z5 }suppression techniques to be evaluated, despite possibly changing bias points or tank Q,
% e7 s- t, `0 s5 A6 ?" r# gwhich 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
2 ^# @' G3 |; U9 m: Q* vcircuit (which is essentially a tracking ADC) which repeatedly adjusts the relative N to P
7 H* e0 f9 I. `' Rwidth dependent on the ΛDC estimate to maintain the condition of minimum flicker noise
4 {" k) L; ~- I5 ~upconversion. A fixed calibration constant is sufficient to allow convergence to within
0.7dB 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
of cycling to accumulation to be applied to continuous time oscillators, but is not
rigorously vetted.