# 1a Poor communication - Customer either has no real idea of how he wants to use the chip, or does not know which parameters are really critical and so leaves some unspecified, until he uses the chip in the app and then realizes
#1b Poor system design - The above can also be counted as poor system design.
In the end, the customer refuses to take the chip, and so effectively, the chip is dead even if it meets all your specs as specified.
#2 Poor understanding of parameters: For instance, what exactly is meant by DC gain and how much do you need, and why? I have often heard people discuss how they need >120 dB DC gain, but only 70 dB settling accuracy will do. DC Gain means nothing, it is the accuracy to which the opamp inputs settle that counts. People learn this the hard way by measuring their chip results, and/or when they begin designing gain-boosted opamps and run head on into doublet-related settling issues
![Smiley Smiley](https://designers-guide.org/forum/Templates/Forum/default/smiley.gif)
#3 Muxing testmode pins onto analog pins without giving a thought to what might happen there in normal mode
#4 Forgetting about the voltage range that a switched-cap circuit can handle. People forget about this, and get "mysterious" errors from charge-pumping action."
#5 Poor layout: Despite the well-known fact that fully differential circuits are not fully differential unless you have made a perfectly matched layout, people go on laying things in strange and sometimes downright unacceptable configurations, and then see even-order distortion, noise problems etc.
A lot of the problems can be classified as system-level issues. The list of such things could go on endlessly of course.
Regards
Vivek