A related question is a question created from another question. When the related question is created, it will be automatically linked to the original question.
If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
OPA1652 and OPA2171 are CMOS op amps and as such they do NOT exhibit popcorn noise. OPA2140 has a JFET input differential pair but bipolar active load which may be prone to popcorn noise - for this reason entire OPAx140 and OPA141 families of op amps are being screened at the final test.
No single source of popcorn noise is theorized to explain all occurrences, however, the most commonly invoked cause is the random trapping and release of charge carriers at thin film interfaces or at defect sites in bulk semiconductor crystal. Since unlike in bipolar transistor where there is a significant base current (nA to uA) and electrons travel across p-n junction (where they may randomly get trapped), in CMOS technology there is virtually no gate current (fA) and therefore no 'opportunity' for the electron trapping and thus no popcorn noise.
For more information regarding popcorn noise, please read the attached article.
We are currently designing in new opamps into a client design for a medical diagnostic product. The client has had issues with popcorn noise with the currently used AD822 opamp. The client wants some kind of assurance that moving to a new part, such as the OPA2132 or OPA2140 will either eliminate or greatly reduce the possibility of this popcorn noise causing manufacturing failures. There are about 320 of these opamps used per device, so even though the yearly device manufacture numbers are low, a significant number of opamps are utilized.
As I had mentioned previously, the best way to avoid the problem with popcorn noise would be to use our CMOS op amps, like OPA1652 or OPA2171, that do NOT exhibit this problem.
OPA2132 and OPA2140 use JFET input differential pair together with bipolar transistor active loads that may be prone to the popcorn noise issue. Although we perform a comprehensive popcorn screening of OPA2140, no such screen test is 100% proof. Since the actual pops may occur at long-time intervals (like minutes or longer apart), it would take unreasonable amount of test time (resulting in very high cost) in order to assure popcorn-free performance and even this would not be 100% effective for pops occurring at time intervals longer than tested for.
All in all, our popcorn screen test greatly reduces the odds of shipping OPA2140 units showing popcorn noise but does NOT completely eliminate possible test escapes since it does not detect the units with pops occurring at long-time intervals. For this reason, if your customer cannot use our popcorn-free CMOS op amps, he may use popcorn screened OPA2140 with the understanding there might be some test escapes or consider using op amps like OPA2132 or OPA2134 which by virtue of their much larger transistor geometry are less likely to suffer from the popcorn noise problem.
