Experimental Validation of Device Sizing on CMOS LC-VCO Phase Noise

• This work investigates the impact of device sizingon phase noise in CMOS LC-tank oscillators, based on specificdesigns and careful measurements. It experimentally verified thepreviously published equations and clarified some conflictingdesign guidelines. The conclusions are grounded on the faircomparison of seven VCOs with the core device width varyingfrom 40 um to 280 um. These VCOs are originated from the samedie by using Focused Ion Beam (FIB), guaranteeing the sameorder of process variation. With the aid of a switched capacitorbank, they are able to operate at practically same oscillationfrequency under the same bias. These conditions assure the faircomparison. It validated that phase noise from tail devices isstrongly dependent to core device size (14 dB from measurements)while phase noise from core devices themselves shows smallerdependence (4 dB). Design guidelines, applying to different tailnoise cases, are concluded and generally advise the minimumcore device width especially when tail noise is dominant.

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Elektroteknik och elektronik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Electrical Engineering, Electronic Engineering, Information Engineering (hsv//eng)

Keyword

Oscillators

sizing

phase noise

LC-tank

CMOS

Publication and Content Type

vet (subject category)

ovr (subject category)