| 摘要 |
A resistor ladder (10) includes a plurality of series resistors (16,18,20,22,24,26,28) connected in series with each other between a first terminal (12) and a second terminal (14). A plurality of shunt resistors (60,62,64,66, 68,70) are connected between junctions (48,50,52,54,56) of adjacent series resistors and the second terminal (14). The series resistors (16,18,20,22,24,26,28) and shunt resistors (60,62,64,66,68,70) are formed on a substrate (80) as film resistors which blow open at a predetermined current density. The shunt resistors (60,62,64,66,68,70) have a smaller cross-sectional area than the series resistors (16,18,20,22,24,26,28) such that they successively blow open from the first terminal (12) toward the second terminal (14), while the series resistors (16,18,20,22,24,26,28) do not blow open, as a progressively increasing voltage is applied between the first terminal (12) and the second terminal (14). The resistance of the ladder (10) increases as the shunt resistors (60,62,64,66,68,70) are successively blown. The shunt resistors (60,62,64,66,68,70) preferably have twice the resistance as the series resistors (16,18, 20,22,24,26,28), enabling the resistance of the ladder (10) to be electrically trimmed in increments equal to the resistance of each series resistor (16,18,20,22,24,26,28).
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