Fully integrated RF VCO for wireless transceivers

Abstract

Iiideung terms VCC), integrated inductor. phase iioise .A I3 ST R A CT I NTR ODU CTI ON A t all RF wireless applications where we have to iriiplement VCOs the resonators are critical parts of the systcm. Using off-chip solutions \\'ill cause problems with packaging, the pwxiitics of the packages will be part of the rcsoiiator circuitry so their accurate modeling is ii must [ I ] . Furthermore the package wdl c;iIisc unwanted couphgs between the rcsonator pins where large RF currents can be prcscnt and other parts of the circuit. On-Chip resonators are good candidates to avoid packaging probkms. The most common intcgratcci rcsona[ors contain simple intcgratcd spirals which suffer from the low quality factor dui. to the ohmic and substrate losses. Their typical Q is around 4-5 at 2GHz on high ohmic silicon substrates. [2]To r-cducc the substrate losses we employed a special structure to block the parasitic eddy currmts in the substrate responsible for the stitxtratc losscs. Our method resulted in 15% increase in the quality factor of the spirals which enabled us to achieve improoved phase noise performdnce with this hlly integrated oscillator circuit.

A study of phase noise in colpitts and LC-tank CMOS oscillators

“…While the classical differential LC-tank oscillator, in one or another of its many variants, has become the standard choice in the RF community, the differential Colpitts oscillator has also been the subject of several recent works (see e.g., [1], [2], [4], [5], [3]), in the reasonable attempt of extending the outstanding phase-noise performances of single-ended Colpitts oscillators to differential versions as well.…”