amplify 40kHz audio signal using TL082: first two stages are fine, but high noise from the third stage

Hello Larry,

That's what I always hope for but sometimes it never happens, other times that price decline is too slow. Take the AD603. It actually seemed to have gone up a little bit. Well, it doesn't have any competition and its market is kind of small. So I did a lot of these designs with transistors and PIN diodes. One upside with that approach is that you can achieve a dynamic range from here to the Klondike, almost like what tubes can do.

Yes. Typically 90% or more of the stuff that receives glitz and glamour in EE Times or EDN is off limits in that design field. Plus nearly anything that is single source.

Somebody messed up their algorithm? The AD603 is quite remarkable in noise figure. But I usually have a preamp in front of it with a "hot rod" RF transistor. Just to squeeze out the last dB.

Regards, Joerg

In article , Joerg wrote: [.. snip ..]

Yes, depending on other factors, you need a wide bandwidth if you need to resolve multiple targets.

In the marine case, some side scan sonars effectively end up with a narrow band width. The data from several pulses are averaged together to improve the SNR.

It also depends on how you define "wide band". The signal is all within the same decade, in most such systems. There is usually as you said 2-3 cycles at least. In a few systems, the bandwidth really is wide and the signal can't really be said to have cycles. There is more than one zero crossing but the time between them increases as you go along.