2SC2240 Equivalent

[Mark Tillotson]

I also suspect "pulse noise" is popcorn noise, which is independent of actual noise figure as its due to defects in the crystal or its surface, not the fundamental properties of the device.

 

[wg_ski]

Defects in the crystal structure = a bad transistor. Like a bad 2SC458.
”Woke last night to the sound of thunder” - means you left the stereo on when one of those starts giving you fits.

 

[Mark Tillotson]

We're talking individual atomic sized defects, typically on the surface (which is why buried structures are used for low-noise devices). Individual charges can get stuck on these defects, then get knocked out again, then get stuck again - leading to discrete changes in the local electric field - popcorn noise and flicker noise are mainly due to this sort of thing.

The kind of bad transistor you describe has actually deteriorated somehow.

 

[rsavas]

Does that explain the reported popcorn noise for the lm4562 opamp? Does Doug Self ever mention this in any of his writings?

 

[Mark Tillotson]

It explains every semiconductor device with popcorn noise I think. Doug mentioned the EMI sensitivity, can't remember what he said about noise.

 

[jitter]

A

Does that explain the reported popcorn noise for the lm4562 opamp? Does Doug Self ever mention this in any of his writings?

I think all semiconductors more or less suffer from this problem.
In a particular application, I needed to replace about 10% of the AD797 because of popcorn noise taking the device (measuring instrument) in which it was used out of spec.
I think I have a similar problem with my amp right now, the right channel suffers from some very light crackling noise.