Application of the 1-D silicon limit to varactors

Solid-state varactor performance is evaluated in light of fundamental tradeoffs imposed by semiconductor material. This leads to the important conclusion that the product of Q factor, frequency, tuning range, and breakdown voltage has an upper limit (between 5 and 40 THzmiddotV for silicon) that is dictated primarily by semiconductor material parameters, and to a lesser degree on doping level and temperature. This limit is then approached by experimental hyperabrupt profiles with a product of 17 THzmiddotV that were fabricated in a SiGe BiCMOS process. Two complementary analysis techniques based on LCR and high-frequency measurements are presented