Patent ID: 6984869

Claim:
A diffusion resistor comprising: a substrate containing a well; a diffusion region formed within said well, said diffusion region having predominantly p-type dopants; a first contact region and a second contact region, both of said first and second contact regions extending down from a surface of said substrate and containing predominantly p-type dopants; a third contact region and a fourth contact regions, both of said third and fourth contact regions extending down from said surface of said substrate and containing predominantly n-type dopants, wherein said third and said fourth contact regions are located between said first and said second contact regions, said third and fourth contact regions defining a conduction channel therebetween; and first, second, third, and fourth contacts attached respectively to said first, said second, said third, and said fourth contact regions; wherein said first contact and said second contact form terminals of said diffusion resistor; wherein said third contact and said fourth contact each forms a diode such that application of a voltage to said third contact and said fourth contact forms respective depletion regions that change in size depending on a value of said voltage; whereby a resistance in the depletion resistor is changed by changing said voltage.