New chopper opamp from AD ADA4523-1

[RandallMcRee]

Lower noise than the ADA4522. Lower bias current, too. Now we need the -2 dual....
https://www.analog.com/media/en/technical-documentation/data-sheets/ada4523-1.pdf
https://www.analog.com/en/products/ada4523-1.html

[Vgkid]

Looks like it will be a nice part.

[Kleinstein]

It is a nice part in some cases, but the low voltage noise comes at the price of a high current noise and high supply current. So it is good for low impedance (e.g. < 10 K) only. At 10 K the ADA4522 may already be the better choice.

Due to the high supply current a dual version makes no sense. Already now heat can be a problem when used with a higher supply.

[RandallMcRee]

Hmmm, not sure why you say these things. Input current noise is not optimized for either of these parts and is quite close for both.
Second, Iq for a dual seems well within the range of other duals that are in the precision range...as you can see from the selection.

[Kleinstein]

For high DC precision one wants low temperature gradients and thus low power. So 4.5 mA, especially at higher voltage are a real downside. One would not like 9 mA at some 30 V and thus some 270 mW from a part for the 100nV range.  Using 2 chips would be a small price for half the local heating.
The ADA4522 is at some 850 µA only and thus about 1/5 the power. Even there the heat is a downside for using the dual version. There could be a small advantage (but also some disadvantage) from having only one frequency in a dual chip. The high current OPs listed are more like low noise, but not precision types.

For the current noise, I somehow got wrong data ( ? old data sheed) in my table for the ADA4522  . It also has quite some current noise and the cross over is at some 45 K, where the ADA4522 would give similar total noise.

[awallin]

I think I used OPA2188 last time for a PLL where DC-accuracy might be useful
https://www.ti.com/lit/ds/symlink/opa2188.pdf  (first dated 2011, so 9 year old design?)

the AD part has 10nV/C offset while OPA2188 is 30nV/C
AD voltage noise seems about half of the OPA2188..

[RandallMcRee]

I ordered some of these (ADA4523-1BRZ) for testing directly from AD. Minimum qty was 100...

So about 50 available to interested parties for the same price as I paid, etc.

Note: as some of you know it is unfortunately quite inconvenient, not to mention expensive, to send packages to overseas from the US. Ideally if you are in Europe and would like one or more of these indicate if you are willing to send some on to others also in Europe.

PM me.

Randall (Davis, CA, 95616)

[macaba]

Crunching the numbers for overall noise in a 0.1-10hz LNA circuit, this looks to be a decent OA on paper:

Using LT1007/LT1037 as x1.00 baseline for overall noise, with a 1.5k resistor in the 0.1hz filter (the largest contributor to noise):
ADA4528-1: 1.23x
ADA4523-1: 1.08x

As long as there is no undesirable behavior, the ADA4523-1 would make a good selection for an LNA. Benefit over the other two; it has the addition of datasheet specified EMI filtering behavior.

Edit: ADA4528-2 (i.e. 2 amps in parallel with the increased BOM cost of passives): x1.06 [margin of error on this is larger, not entirely sure how to calculate this given the 2 amps share the same 1.5k resistor]

[splin]

I ordered some of these (ADA4523-1BRZ) for testing directly from AD. Minimum qty was 100...

So about 50 available to interested parties for the same price as I paid, etc.

Randall, thank you for going to the trouble of making this kind offer. I received mine, as have been those I forwarded to the Netherlands.

I appreciate that it can be quite a pain organising group buys like these having to find shipping costs, dealing with customs declarations and endless email exchanges to sort out the details - including agreeing what happens if the items get lost in the post. So thanks again.

[GL1381]

Do you still have ADA4523-1BRZ? I need it for a special project but am not able to get it due to part lead time problem
Thanks,

[RandallMcRee]

Do you still have ADA4523-1BRZ? I need it for a special project but am not able to get it due to part lead time problem
Thanks,

I have a few left but Mouser is your best bet. They have some in stock.

Randall

[jbb]

I use ADA4523-1 into my V7E-42...

One of these parts is not like the others :-)