A laterally diffused metal oxide semiconductor field effect transistor, LDMOSFET, semiconductor device (200,1100, 1300), comprising: a semiconductor substrate (210,1110, 1310) having a first conductivity type and a top substrate surface (212,1112, 1312); a buried layer (220,1120, 1320) below the top substrate surface, wherein the buried layer has a second conductivity type that is different from the first conductivity type; a sinker region (222,1122, 1322, 1610, 1710) between the top substrate surface and the buried layer, wherein the sinker region has the second conductivity type and is formed as a ring that surrounds an active area, and an isolation structure is formed by the sinker region and the buried layer; an active device in a portion (230,1130, 1330, 1520, 1620, 1720, 1820) of the semiconductor substrate contained by the isolation structure, wherein the active device includes a drain region (236, 1136, 1336) of the second conductivity type and a drift region (232, 1132, 1332) of the second conductivity type; and a diode circuit connected between the isolation structure and the drain region and comprising a Schottky diode (346, 446, 546, 1245, 1445), formed from a Schottky contact (246, 1145, 1345) coupled with the isolation region; wherein, the Schottky contact is positioned at a first portion of the ring, and the device further comprises: one or more additional Schottky contacts positioned at portions of the ring that are spatially separated from the first portion and from each other; and a plurality of further regions of the first conductivity type extending from the top substrate surface into the sinker region at a top surface of the sinker region, wherein the plurality of further regions are positioned at other portions of the ring that are interspersed between the Schottky contacts. a semiconductor substrate (210,1110, 1310) having a first conductivity type and a top substrate surface (212,1112, 1312); a buried layer (220,1120, 1320) below the top substrate surface, wherein the buried layer has a second conductivity type that is different from the first conductivity type; a sinker region (222,1122, 1322, 1610, 1710) between the top substrate surface and the buried layer, wherein the sinker region has the second conductivity type and is formed as a ring that surrounds an active area, and an isolation structure is formed by the sinker region and the buried layer; an active device in a portion (230,1130, 1330, 1520, 1620, 1720, 1820) of the semiconductor substrate contained by the isolation structure, wherein the active device includes a drain region (236, 1136, 1336) of the second conductivity type and a drift region (232, 1132, 1332) of the second conductivity type; and a diode circuit connected between the isolation structure and the drain region and comprising a Schottky diode (346, 446, 546, 1245, 1445), formed from a Schottky contact (246, 1145, 1345) coupled with the isolation region; wherein, the Schottky contact is positioned at a first portion of the ring, and the device further comprises: one or more additional Schottky contacts positioned at portions of the ring that are spatially separated from the first portion and from each other; and a plurality of further regions of the first conductivity type extending from the top substrate surface into the sinker region at a top surface of the sinker region, wherein the plurality of further regions are positioned at other portions of the ring that are interspersed between the Schottky contacts. one or more additional Schottky contacts positioned at portions of the ring that are spatially separated from the first portion and from each other; and a plurality of further regions of the first conductivity type extending from the top substrate surface into the sinker region at a top surface of the sinker region, wherein the plurality of further regions are positioned at other portions of the ring that are interspersed between the Schottky contacts.