Patent ID: 8624683

Claim:
A semiconductor device comprising: a semiconductor substrate; and an LC-tank VCO formed over the semiconductor substrate, wherein the LC-tank VCO includes: a first spiral inductor coupled to a first node; a second spiral inductor coupled to a second node; and a first MOS varactor coupled to the first node; a second MOS varactor coupled to the second node; a first MOS transistor having a drain coupled to the first node and a gate coupled to the second node; and a second MOS transistor having a drain coupled to the second node and a gate coupled to the first node, wherein as seen perpendicularly to the semiconductor substrate, the first MOS varactor and the second MOS varactor are arranged between the first spiral inductor and the second spiral inductor, and the first and second MOS transistors are arranged between the first and second MOS varactors, wherein, as seen perpendicularly to the semiconductor substrate, the first MOS varactor and the second MOS varactor are arranged at a position within a zone sandwiched between a first straight line and a second straight line, wherein the first straight line is a straight line coupling one point on an outer edge of the first spiral inductor which intersects a straight line that is perpendicular to a straight line coupling a center of the first spiral inductor, and a center of the second spiral inductor and passes through the center of the first spiral inductor, and one point on an outer edge of the second spiral inductor which intersects a straight line that is perpendicular to the straight line coupling the center of the first spiral inductor and the center of the second spiral inductor and passes through the center of the second spiral inductor, and wherein the second straight line is a straight line coupling the other point on the outer edge of the first spiral inductor which intersects the straight line that is perpendicular to the straight line coupling the center of the first spiral inductor and the center of the second spiral inductor and passes through the center of the first spiral inductor, and the other point on the outer edge of the second spiral inductor which intersects the straight line that is perpendicular to the straight line coupling the center of the first spiral inductor and the center of the second spiral inductor and passes through the center of the second spiral inductor.