On Wed, 30 Oct 2019 13:58:13 +0000 (UTC), Ralph Barone > wrote:
>> On 29 Oct 2019 11:28:57 -0400, (Scott Dorsey) wrote:
>>> geoff > wrote:
>>>> On 29/10/2019 8:04 am, gareth magennis wrote:
>> This mechanism exists in all electrical conductors, but is only an issue
>> in microcircuits because the
>> conducting lines are so small and the current densities are therefore very high.
>I was under the impression that electromigration was only an issue in
>modern microprocessors and other ICs built using nanometer scale
>transistors. I would assume that an op amp is built with huge transistors
>(and huge traces) in order to achieve low noise, and would therefore be
>relatively immune to electromigration damage.
Nope, electromigration has always been a concern and is one of the two most important reliability
issues in layouts. The other being electrostatic discharge. Huge traces is a relative term, microcircuits
Besides, large interconnect traces result in large parasitic capacitances which have a major impact on
AC charateristics (phase margin, BW, etc.), not to mention the impact on chip size and therefore
chip cost. Also, bipolar amps don't use large devices to reduce noise.