FLICKER NOISE IN CMOS LC OSCILLATORS国外硕士论文

qitianhua

A Thesis Presented to The Academic Faculty
# z# H; \1 v" v1 zBy Dale Scott Douglas In Partial Fulfillment Of the Requirements for the Degree
Master of Science in Electrical and Computer Engineering
Georgia Institute of Technology
: V) j7 H9 b  s& N+ ODecember, 2008

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SUMMARY
0 X. Y! v0 v, d  l  x0 DSources of flicker noise generation in the cross-coupled negative resistance oscillator
  O2 ^5 m& I" g# m(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
2 M* w# R- c) g0 @- Q4 R& ]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
9 e+ Q& }% p6 [' Tdeveloped, which allows a new quantity, FOM1, to be defined. FOM1 is proportional to
flicker noise upconverted, thus allowing the effectiveness of flicker noise upconversion
; e. f) m) t0 Bsuppression techniques to be evaluated, despite possibly changing bias points or tank Q,
which would change phase noise and FOM in the 1/f2 region.
) V8 t( B; o/ ]4 \' l; LThe 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
6 n- [, o0 e5 @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
# f& B6 f' W: b6 }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
0 p1 c' F3 C  _: v7 I2 z8 I3 ]of cycling to accumulation to be applied to continuous time oscillators, but is not
rigorously vetted.