2) The harmonic distortion is based on the reference circuits. They are not very sophisticated.
3) The LT1166 is a bias current IC. This is not easy to do by other means.
4) Especially if you are putting out tens of kilowatts to drive a US Navy Active Sonar based on
Terfenol-D with Analog FETs. And the spec does not allow crossover distortion when the water
to the water cooled heat sink fails due to battle damage.
Oh - you want a finished product that happens to have the chip in it? Not the chip by itself? Linear Technologies may still be able to help by telling who bought them for that purpose.
Otherwise that's not an easy answer. Maybe find an audio enthusiast blog?
Yes I posted on DIY Audio. No joy. LT has, I think, a spice model and I'm going to LTSpice an audio circuit. But I don't totally trust Spice and want to do some real live testing.
I can't see your system spec from here, but it would seem to be relatively simple from the system design perspective to use a digital class amplifier and add shielding and filtering, and still end up with a better solution than an analog amplifier in the 'tens of kilowatts' class. Maybe. Maybe not. It should not be rejected outright.
Keep in mind that you're going to need filtering and shielding in spades anyway to keep the kHz (?) sonar signal itself (meaning the conducted and radiated EMI emissions from the system and its wiring) in check anyway. MHz switching noise is probably easier to filter and shield than your kHz primary signal with 'tens of kilowatts'.
Plus, the system is likely to require a massive power supply, which would presumably be switching (as opposed to linear) these days. So there's going to be some switching I'd think.
If the amplifier can be installed next to the transducer, in the depths of a Navy ship, then it should be easy to keep the EMI in check.
Just some thoughts in case they help. Cheers.
PS: I did use my best Google-Fu on your original post, but found nothing.
"Class D. Military, EMI. Switching amplifiers a No-No!"
This is not true, in general. The motors in the modern submarines are commutating megawatts of power, and couldn't even begin to be efficient if the drivers were class AB.
Moreover, even if you used a class AB, you'd still be running as digital, as there is no plausible operational requirement to halfway between the rails during operation, and under normal operation, being in the middle costs a truckload of inefficiency, which a military system can ill afford.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!
Requirements trump the laws of physics, of course...
Figure 14 of the datasheet shows you how to scale up their topology to handle higher powers. Hypothetically, 30 "slices" would get you about 9 kW. However, at that point, you might need a slice to buffer the front end as well.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!
