Pro Audio Design Forum

What can be expected with offset compensation with a trimmer ? For instance considering OPA2277: Vos 20µV typ, 65µV max Vos drift 0.15µV / °C Can I expect with proper trimming a final Vos based on drift only. Considering à 10°C to 60°C temperature span, if trimmed at 35°C, this would give about 4µV ...

To minimize loop area this is an interesting way, however there are other objectives. Some components better be on the same side of the PCB for better thermal matching. It is likely there is less temperature gradient for components close on the same side rather than closer but on opposite side. Prac...

opportunity pricing around the internets... This drives me mad. They heavily do it on air flight prices. Years ago I was used to book from an internet travel agency, until I noticed that if I was not bying right away, prices were jacked up, the next times looking for the same flights. Now, I forgot...

Change from previous schematic: Added R32 and R33. +15 mV is developed across R33 to satisfy an estimate of the common mode bias current of Q1 and Q2. What good is removal of common mode biais current of Q1 and Q2 ? This + 15 mV lifts the inputs close to ground, removing DC at the source input, is ...

In my quest for low Input Voltage Offset, a key point for an integrator circuit, I lost hope in matching op amps. What is better than OPA2277 ? Are they better ones, at low input voltage offset ? Is chopper op amps the way to go, in audio applications ? EDIT chopper op amps like: Zero-drift amplifie...

I found, offset voltage matching does exist:
https://www.analog.com/media/en/technic ... LT1002.pdf
Guaranteed LT1002A 60µV max offset voltage
Guaranteed LT1002A 40µV max offset voltage matching
This data is disapointing, I was expecting much better from matching.

An interesting paper about Vos Ios Ibias, how they come in the output offset of a FDA circuit using THS4551. https://e2e.ti.com/blogs_/b/analogwire/archive/2016/12/08/what-you-need-to-know-about-input-bias-current-and-why This shows, on the given example: Vos is the major contributor onto the output...

In the design of an integrator circuit whether it is a Deboo or another implementation, a most important op amp characteristic is low Vos. For a balanced integrator that uses two op amps, the two Vos, if exacly equal, would provide an integrator with 0 Voltage input offset. Does it make sense to mat...

Great to see you have a final proto with final measurements.
What about the noise from the servo ?
At the op amp output
At C6
The effectiveness of noise removal by the 100 nF cap.

An after thought about my statement: "A peak led is a must on a preamplifier board". When not implemented on the preamplifier boards, adding peak led and vu meter drivers afterward gives a not so clean chassis wiring. OTOH, there are many variants about what users like to add or not. To ke...