Patent ID: 7692271

Claim:
A junction varactor, comprising: a single first silicon region formed in a silicon substrate, said first silicon region of a first dopant type, a concentration of dopant of said first dopant type in said first silicon region increasing with increasing distance into said substrate from a top surface of said silicon substrate; a plurality of second silicon regions in physical and electrical contact with said first silicon region, said plurality of second silicon regions spaced apart and not in physical contact with each other, said plurality of second silicon regions of a second dopant type, said first dopant type different from said second dopant type, said second silicon regions isolated from direct electrical contact with each other by dielectric isolation regions formed in said substrate; a buried plate in said silicon substrate, said first silicon region in contact with said buried plate, said first silicon region between said buried plate and said top surface of said silicon substrate, said buried plate doped said first dopant type; a cathode terminal electrically connected to said first silicon region; a first anode terminal electrically connected to a first set of second silicon regions of said plurality of second silicon regions; and a second anode terminal electrically connected to a second set of second silicon regions of said plurality of second silicon regions, second silicon regions of said first set of second silicon regions alternating with second silicon regions of said second set of second silicon regions.