Small- and large-signal RF characterization of fully-depleted accumulation-mode varactors for low-voltage LC-VCO SOI design

Small- and large-signal RF characterization of fully-depleted accumulation-mode varactors for low-voltage LC-VCO SOI design ■

Bertrand Parvais, Bertrand Parvais, P. Delatte, P. Delatte, H. Matsuhashi, H. Matsuhashi, F. Ichikawa, F. Ichikawa, P. Simon, P. Simon, D. Schreurs, D. Schreurs, D. Flandre, D. Flandre, J. P. Raskin, J. P. Raskin

Abstract ■

The evolution of the varactor sensitivity k v between small- and large- signal regimes and its consequences to the voltage-controlled-oscillators (VCO) design were discussed. It was found that when V GS was going towards negative values, the zero-Vt varactor depleted rapidly giving a sharp C-V curve. The fine-tuning curve of a 2.45 GHz LC differential VCO including the characterized varactor was measured as a function of the bias current. Analysis shows that the tuning curve of a low-power 2.45 GHz VCO is in good agreement with predictions made using DF theory.