Patent ID: 7071811

Claim:
A diffusion resistor comprising: a substrate; a diffusion region formed in the substrate; a first contact region extending down from a surface of the substrate; a second contact region extending down from the surface of the substrate; a first conductive contact electrically connected to the first contact region such that current can flow between the first contact and the first contact region; a second conductive contact electrically connected to the second contact region such that current can flow between the second contact and the second contact region; and a third contact connected to the surface of the substrate and electrically isolated from the first conductive contact and the second conductive contact, wherein the third contact is located between the first conductive contact and the second conductive contact, wherein the third contact forms a Schottky diode with a voltage being applied to the third contact to form a depletion region that changes in size depending on the voltage applied to the third contact to change a resistance in the diffusion resistor, wherein the first conductive contact and the second conductive contact form two ends of the diffusion resistor with no bias voltage on either of the first conductive contact and the second conductive contact.