Patent ID: 10325905

Abstract:
In a constant voltage clamping circuit, a p-type anode region and an n-type pickup region are provided separated from each other in an n−-type well region. In the p-type anode region, a p−-type low-concentration anode region is provided. In the p−-type low-concentration anode region, an n+-type cathode region is provided. A first Zener diode of a highest potential of the constant voltage clamping circuit is formed by a pn junction of the p-type anode region, the p−-type low-concentration anode region and the n+-type cathode region. An n+-type pickup contact region in the n-type pickup region is arranged at a position near the n+-type cathode region and separated farther the n+-type cathode region, from p+-type anode contact region. The n+-type pickup contact region and the p+-type anode contact region are short-circuited.