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
) N( f* e% E9 SMaster of Science in Electrical and Computer Engineering
Georgia Institute of Technology
December, 2008


SUMMARY
Sources of flicker noise generation in the cross-coupled negative resistance oscillator
8 @7 S2 K8 n* G: [0 I0 _; `9 R, k(NMOS, PMOS, and CMOS) are explored. Also, prior and current work in the area of
3 I( h- ?5 [) o8 f! \6 Vphase noise modeling is reviewed, including the work of Leeson, Hajimiri, Hegazi, and
9 ?( I& A! m4 z$ B# U# ^others, 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
( h. \, F0 ~5 J7 r, e3 ^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
' G$ M/ \+ R( z! |8 V' v! Z, N; rsuppression techniques to be evaluated, despite possibly changing bias points or tank Q,
which would change phase noise and FOM in the 1/f2 region.
6 @6 u: ~5 d; s6 `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
) C1 U6 }* L* q8 G4 P: N7 k! S' Qwell, 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
- e. ?* O* ^! B$ E& z  b0 ~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
0.7dB of optimal FOM1 for all cases of N width, for a varactorless oscillator test cell.
5 z, L. Y& q8 Z3 N8 iFinally, 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.