OPA2626: Strange behavior of OPA2626

Hello,

Could you try running the OPA2626 simulation in split-supply configuration?  While the models are designed for TINA-TI and SPICE, TINA-TI can be easier to use for some circuit configurations.  

The OPA2626 does not have a fully rail-to-rail input range, only going down to V- (GND) and not up to V+ (3V3).  You will need to make sure your inputs do not violate the input common mode range.

Best,

Alec

Hello

I split the power supply, and the result is very strange.

From the datasheet, Vcm could be 3.3-1.15 = 2.15V

in 1st amp, Vcm = 0.136V

in 2nd amp, Vcm = 1.6V

it is in the spec range.

I split the power supply to +/-2.7V, the result is still not good. I doubt the model is correct or not?

Hello,

The screenshot below shows the values I am getting at your measurement points during a DC bias point simulation:

Best,

Alec

Hello

That is the problem. The gain of first amp is -10V/V. The output should be 100mV. But what you see is 60.32mV.

That is what I don't understand. 

Hello,

Could you try simulating your circuit with OPA810, TLV365 and OPA607 models?  I am curious if the ADC driving focus on the OPA2626 device makes its model behave oddly in non-ADC driving configurations.

Was there a particular reason you were looking to use OPA2626?  We have duals of other op-amps, such as OPA2810, TLV2365, and the OPA2607.  You can use the OPA2607 for both op-amps stages as you have gain configurations greater than the minimum stable gain.

Best,

Alec

I try OPA810 first

The result is not correct. That is because the voltage at U1 IN+/IN- are not the same.

TLV365 do not provide a pspice model, I do not perform a simulation

OPA607 give the correct result.

I do not have a reason for dual channel Op Amp. But a dual channel Op Amp is an add value.

Thanks!

I am looking for a high speed amplifier, >=100MHz. 3.3V power supply. and the offset should be lower. I think OPA2626 is good choice.

At beginning, I try to use OPA838. However, it is decompensated. It is not very stable.

I would like to use OPA2626 as a substitute for ADI ADA4807

I think the simulation result is not correct.

Hello,

Thank you for the new data.  Allow me some time to simulate and investigate. 

We should be able to use on of our high speed amps to substitute for ADA4807.

Best,

Alec

Hello Alec

I am OK with your explanation. I try 100/1kohm for the simulation. The result is much better.

Due to I already try to balance the impedance at Invert Input and Non-Invert Input? I think the major is input offset current rather than input bias current.

I do not see an obviously difference between OPA2626 & ADA4807. But I would say the result of ADA4807 is much better. I understand it may mainly from model difference but not the part difference.

And I tried OPA625, the result is good. I use the high drive mode.

I guess OPA625 is very similar as OPA2626. So I expect a good result of OPA2626. My question is if the test result of OPA2626 is good. Can I ignore the simulation results. Or how many OPA2626 should I test?