Discrete Opamp Open Design

[bcarso]

Originally Posted by Wowozange

For all interested, a new book appeared:

Matthias Rudolph, Christian Fager - Nonlinear Transistor Model Parameter Extraction Techniques. ISBN: 0521762103 (13 MB )

"Achieve accurate and reliable parameter extraction using this complete survey of state-of-the-art techniques and methods. A team of experts from industry and academia provides you with insights into a range of key topics, including parasitics, intrinsic extraction, statistics, extraction uncertainty, nonlinear and DC parameters, self-heating and traps, noise, and package effects. Learn how similar approaches to parameter extraction can be applied to different technologies. A variety of real-world industrial examples and measurement results show you how the theories and methods presented can be used in practice. Whether you use transistor models for evaluation of device processing and you need to understand the methods behind the models you use, or you want to develop models for existing and new device types, this is your complete guide to parameter extraction."

That looks good, albeit with a heavy RF emphasis. I'd order it in a heartbeat if I felt a little richer

[kgrlee]

Originally Posted by PHEONIX

The Boxall in practice achieves lower THD figures thats why its appealing to use.

Got any simpler examples which demonstrate this?

Super TIS is a ve..ery specialised application that only shows pp zillion THD into 50M & greater loads.

[luvdunhill]

Originally Posted by linuxguru

I just gave the dual, through-hole version for PCB fabrication today - probably a month for bare PCBs and a week or two after that for assembly and test. I'm hoping it will do OK in line stages in CDPs, DACs, soundcards, etc. - anything with a high-Z load. It could in principle drive low-Z headphones with a heftier output pair and higher output stage bias, though it wasn't designed for that.

Meanwhile, I've upgraded the SMD version to use Rohm IMX2/T2A duals in SC74 packages, which have higher (300 mW) Pd. I'll probably send it out for fabrication only after the through-hole version comes back and passes sanity checks.

Interesting, I'd like to play with this one as well, if that would be okay. I could probably even do a two sided version in a SIP-8 dual opamp format, similar to my layout. I could volunteer to look at higher output bias version. As you can see in my prototype, I'm using DIP14/16 heatsinks to bolster the heat dissipation of a SOT223 device. Does anyone have a recommended complementary SOT223 device? I have tried using BCP53-16 and BCP56-16 from On and feel these are good, but would appreciate other recommendations. The SOT223 seems to me to be a good size / Pd tradeoff. If these are good for output devices, then I might buy a bunch.

Also, thanks for the information on how to qualify the design. I'm sure I'll have more questions later, but the gives me enough to go on for now.

[dchisholm]

Originally Posted by luvdunhill

. . . Does anyone have a recommended complementary SOT223 device? I have tried using BCP53-16 and BCP56-16 from On and feel these are good, but would appreciate other recommendations. . . . .

Based on a just the Data Sheets, the NXP PBSS8110Z ( http://www.nxp.com/products/bipolar_....html#overview ) and PBSS9110Z ( http://www.nxp.com/products/bipolar_....html#ordering ) look like possibilities. (The same devices seem to be available in SOT-23 as PBSS8110T/PBSS9110T.) I'd like to know if anybody has first-hand experience.

Dale

[Waly]

Originally Posted by luvdunhill

Does anyone have a recommended complementary SOT223 device?

Fairchild PZTA42/92. Same chip as MPSA42/92.

[luvdunhill]

Originally Posted by dchisholm

Based on a just the Data Sheets, the NXP PBSS8110Z ( PBSS8110Z :: NXP Semiconductors ) and PBSS9110Z ( PBSS9110Z :: NXP Semiconductors ) look like possibilities. (The same devices seem to be available in SOT-23 as PBSS8110T/PBSS9110T.) I'd like to know if anybody has first-hand experience.

Dale

I'm using the NXP models for both these and the BCP and it doesn't do as well in my circuit, it's a about a 5dB difference.

The PZTA is heading in the right direction though, though I had to null out way more DC offset than with the other two candidates. Again, I used the NXP models. I wonder what qualities of the PZTA make it perform better than the BCP? If I can figure that out then I could see if there are models that perform even better.

[dchisholm]

Originally Posted by luvdunhill

I'm using the NXP models for both these and the BCP and it doesn't do as well in my circuit, it's a about a 5dB difference.

5 dB difference in what parameter?

Dale

[dchisholm]

Originally Posted by Waly

Fairchild PZTA42/92. Same chip as MPSA42/92.

The 100 mA max collector current will be a factor to watch carefully if you are serious about driving Lo-Z headphones.

Dale

[luvdunhill]

Originally Posted by dchisholm

5 dB difference in what parameter?

Dale

Output THD @ 20kHz (according to LTSpice)

[PHEONIX]

Originally Posted by kgrlee

Got any simpler examples which demonstrate this?

Super TIS is a ve..ery specialised application that only shows pp zillion THD into 50M & greater loads.

Hello Kgrlee,

Do you have a copy of Dimitri's "Enhanced cascode Article".