Patent ID: 8253506

Claim:
An apparatus comprising: a first node; a second node; a first signal input conductor; a second signal input conductor; a main varactor circuit comprising: a first main varactor circuit portion comprising: a first varactor having a first lead and a second lead, wherein the first lead of the first varactor is coupled to the first node; a second varactor having a first lead and a second lead, wherein the first lead of the second varactor is coupled to the second node, and wherein the second lead of the second varactor is coupled to the second lead of the first varactor at a first control node; and a first analog multiplexing circuit that couples a selected one of the first signal input conductor and the second signal input conductor to the first control node; an auxiliary varactor circuit coupled between the first node and the second node; a first temperature compensation voltage generating circuit having an output lead coupled to the second signal input conductor; and a second temperature compensation voltage generating circuit having an output lead coupled to the auxiliary varactor circuit.