Patent ID: 7759923
Filing Date: 2010-07-20
Classification: H01L

Abstract:
1. A current sense device for a power transistor, the power transistor being formed in a cellular structure including a cellular array of transistor cells, the cellular array comprising a polysilicon layer formed in a mesh and having a plurality of substantially identical openings defining the source and drain regions, the source and drain regions being formed in alternate rows of the cellular array, the drain terminals of all transistor cells being electrically connected by first metal lines in a first metal layer and the source terminals of all transistor cells being electrically connected by second metal lines in the first metal layer and third metal lines in a second metal layer, the current sense device comprising: a plurality of transistor cells in the cellular array of transistor cells of the power transistor being used as sense transistor cells, the sense transistor cells being evenly distributed throughout the cellular array, the drain terminals of the sense transistor cells being electrically connected to the drain terminals of the transistor cells of the power transistor, the source terminal of each sense transistor cell being electrically connected to a first node through a fourth metal line in the first metal layer and through a fifth metal line in the second metal layer, the fourth and fifth metal lines being electrically isolated from the first, second and third metal lines in the respective first and second metal layers, wherein the sense transistor cells measure a small portion of the current flowing through the power transistor based on the size ratio of the current sense device and the power transistor.