Icl 7650 Chopper Input offset problem

[Simon123]

Hy!

I built a simple circuit with this ICL7650SCPD amplifier. I used internal clock.
I chose non inverting confirguration with 10R and 10k resistor, giving me gain of about 1000.
Then I connected non inverting input to GND, and measured the output which was like 100mV.
So this means input offset of 100uV(it should be between 1-5uV). What could be the problem? I assume the problem occurs because i wired everything on breadboard or is there something else?
GND I was using is virtual ground by the way.

[BrianHG]

What's you V+ voltage and V- voltage?

[Simon123]

+5V and -5V (From 10V total).

Edit:
Ok, i forgot bias resistor on non inverting input(watched daves video ).
Now i get like 10mV, that is 10uV offset. I assume i'd get it down to couple uV if i built it on PCB and used guard rings, right?

Ol. now measured it again and its 50mV, 50uV offset.

[Simon123]

Changed setup to 220R/220k and measured voltage across both 220R resistors. I get about 0.5mV on each, and this means current of 2.3uA, WTF? Why do i have so much current flowing to the inputs :s ?

[BrianHG]

Changed setup to 220R/220k and measured voltage across both 220R resistors. I get about 0.5mV on each, and this means current of 2.3uA, WTF? Why do i have so much current flowing to the inputs :s ?

Now, I am assuming you didn't buy your ICL7650SCPD from Ebay, Aliexpress, Alibaba, Banggood, or any other no name place, correct?
Also, you have taken full anti-static precautions?
Also, you are using a quality bread-board which doesn't have current leakage between adjacent pins...

[Simon123]

I measured voltage across that again and now its 0mV, but i still have offset from 20-50uV.
No, i bought the chip from local electronics store.

And im just using regular breadboard for 5€. Its not from ebay, i think its ok quality.
And now i am getting negative output voltages (-33mV atm) ...

Ill make circuit up on veroboard, i hope it removes this offset.

[BrianHG]

Try moving the chip to a fresh new location on your bread board.
Also, measure individual pins to check they are getting all the right voltages.
Also, make sure you have 2 power decoupling caps right on the power pins to GND.
Also, maybe show us a simple schematic of your wiring.
Also, what evidence do you have that your IC isn't a Chinese clone.
And, lastly, what kind and value of caps are you using for cextA and cextB.

[Simon123]

Polyester capacitors.
I moved resistors from one hole to other and now i get -12uV. I guess its the board.

[Simon123]

Ok built everything on veroboard(with ic socket) and i get like 2mV output, which is 2uV
Since 7650 has same pinout as 8 pin dip chips now i can also test offset of those.

[BrianHG]

Also add a .1uf cap between v+ and v-.
And add a .1uf cap between GND and in the middle of the 2x 56ohm resistors.
Things might get a tad better.

[Simon123]

Thanks, i  added capacitors across divider, hard to tell if there is any change, but offset is within spec anyway.