An integrated circuit module is designed with bypass switches in critical places
to route signals around specific circuit blocks, e.g. an automatic gain control
(AGC) system and an anti-aliasing filter. If there had been significant problems
with either block, it can be bypassed and tests of the remaining circuits are possible.
This allows all circuits in the module to be tested in the initial pass, reducing
the risk of needing a third pass after the known problems were fixed in the second
pass. Additionally, the bypass circuits are useful at module production test and
for diagnostics in the final product.
