One-dimensional Networks using Excel

In order to test the operation of the resistive fuses in a network, Microsoft Excel was used to create a large SPICE input file with thevenin equivalent voltage sources connected in a one-dimensional resistive fuse grid. The input data pattern was set by changing the data in the Excel file.

The network was first tested for its resistive behaviour. The input consisted of a flat input voltage with a voltage spike at a central node, short enough that it would not cause any fuses to cut off. The result is shown in Figure 5.1

Figure 5.1: Response of Resistive Fuse Network to Spike Input

The exponential relationship of the output voltage with distance described in Section 3.1 can clearly be seen. The characteristic length can be measured from this diagram as being the intersection of the tangent to the characteristic at zero with the horizontal axis, as shown in Figure 5.2. From the diagram, the characteristic length can be measured to be 2.3. From Figure 4.8, the resistance of the eleven transistor resistive fuse can be measured to be 55k . Thus, the theoretical characteristic length is $L_0 = \sqrt{360/55} = 2.6$. This is only a crude measurement, but it shows that the actual results accord well with the theory.

Figure 5.2: Measurement of Characteristic Length from Network Response.

The network was then tested for its ability to cutoff at sharp changes in input. This is shown in Figure 5.3. The input was made deliberately noisy to show that the network only cuts off at large features, while smoothing uniform regions.

Figure 5.3: Resistive Fuse Network Cutoff Behaviour

This shows that the implementations carried out so far accord well with the theory, and are useful practical circuits.