Electrical trimming of heavily doped polycrystalline silicon resistors

The newly discovered phenomenon of resistance decrease in heavily doped polycrystalline silicon resistors by conduction of high current densiy has been investigated experimentally. Threshold values exist for the impurity concentration and for the applied current density for the occurrence of this phenomenon. Decreased resistance is stable as far as current higher than the threshold value is not applied thereafter. Applications to D/A converters and operational amplifiers are described. Electrical trimming of resistors in the circuits with accuracy of ±0.01 percent is easily attained.