Continued from Digging Into 'DIGIC 4' Image Processor (2).
What are the differences in physical specifications, like dimensions, between the DIGIC 4 and its predecessor, the DIGIC 3?
Again, with the help of Van Partners Corp, we removed the semiconductor package and wiring layers of the DIGIC 3. This time, however, we did not conduct a detailed examination, such as estimation of the number of gates in the logic circuits and the amount of memory, to save time.
The DIGIC 3 was taken out of the PowerShot A470. It is not an expensive camera but has almost the same circuits as of the Ixy Digital series, according to Canon.
We could quickly remove the semiconductor package because the DIGIC 3 had no memory chip. The size of the exposed chip was 6,500 x 6,500 x 220μm. (Please see the table below for more details).
We removed the wiring layers and checked the memory layout.
We saw the cross-section by using the SEM and found that there were six wiring layers.
After measuring the gate length, Van Partners estimated that the DIGIC 3 was designed using a process technology of approximately 130nm.
The table below summarizes the results of the examination. The chip area of the DIGIC 4 is 20% larger than that of the DIGIC 3. It implies that Canon dealt with the increase in functionality, such as H.264 encoding/decoding, by miniaturization and adding wiring layers (See related article). The chip width of the DIGIC 4 is about half that of the DIGIC 3 probably because the former has the PoP structure.
