A device is presented. The device includes a substrate with a first well of a first polarity type. The first well defines a varactor region and comprises a lower first well boundary located above a bottom surface of the substrate. A second well in the varactor region is also included in the device. The second well comprises a buried well of a second polarity type having an upper second well boundary disposed below an upper portion of the first well from an upper first well boundary to the upper second well boundary and a lower second well boundary disposed above the lower first well boundary, wherein an interface of the second well and the upper portion of the first well forms a shallow PN junction in the varactor region. The device also includes a gate structure in the varactor region. The upper portion of the first well beneath the gate structure forms a channel region of the device. In depletion mode, a depletion region under the gate structure in the channel region merges with a depletion region of the shallow PN junction.