ABSTRACT
Ï2 - value of resistor n after trim as shown in Figure 4-16b. Notice that each corner is equal to 1/2 square.
The number of squares in resistor r2
Total number of squares in resistor RT
and also
Solving for L2 gives
Top-hat configuration is also used to minimize number of resistive inks per substrate. It is accomplished by designing a high value thick-film resistor using material with low sheet resistivity. Considering that a large range of dynamic resistance change is not required, the laser trimming is minimized. The resistor design is to final value only. In this case resistance as fired RF = 0.75 RT. Other configurations and trimming options are shown in Figure 4-17.
