A passive laser-trimming technique to improve the linearity of a 10-bit D/A converter

The development of a new laser-trim technique is described. Metal links, which are arranged to provide incremental adjustments to critical circuit parameters, are cut by a laser. Trimming operations are monitored and controlled by means of a computer program. A comparison is made between currently used trimming methods. An application, to improve the linearity of a 10-bit D/A converter, is described. This trimming technique, which is implemented so that its effects track temperature and reference current variations, allows the converter to be adjusted for better than /spl plusmn/0.05 percent linearity by appropriately modifying the ladder termination voltages.