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Two-Stage Current-Feedback Amplifier
AD8011
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Two-Stage Current-Feedback Amplifier
AD8011
Current FB amplifiers are attractive because they are typically very fast and circuit bandwidth is relatively independent of gain. They are typically used for video amplifiers.
The down side for audio use is that, due to their speed, layout and output impedence matching can be critical. These things will oscillate at the drop of a hat. Also, the output impedences are not typically suitable for audio circuits.
The down side for audio use is that, due to their speed, layout and output impedence matching can be critical. These things will oscillate at the drop of a hat. Also, the output impedences are not typically suitable for audio circuits.
I have a couple current feedback amps in my bag. One of them with discrete design had 0.00046% distortion. I recommend that you read some about current feedback because they won't simply work in some applications and the reason is the feedback. The feedback mechanism is different compared to voltage feedback. Walt Jung has a chapter about this in his 1000 pages book "Opamp Applications" which can download from Analog Devices.Onvinyl said:
jcx said:
Yes, there are a couple of newer ones available. But, looking closer, i have not found any that has all the needed features the ad811 has:
- low voltage noise (mandatory)
- low input offset voltage (3mV max, however, I have 8 examples here, all measuring between 0.2 - 0.4mV) (mandatory)
- high slew rate (don't know how important that is at the end of the day, but the ad811 sounds good
)Due to bad PSSR of the ad811, one needs a good PSU, however.
any comments?
Rüdiger
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