You lost me on the loop gain... Can you explain how you got that? Mind you, I'm not taking sides on make vs buy.Yes, you can, but at 1 kHz, you will only have 40 db of loop gain. It depends on what you are trying to do.
Back in the old days, we made instrument amps from the op amps of the days. They worked for our purposes, and some of those applications called for precision performance. AND WE LIKED IT.
And we didn't take the bus to school...we walked through 4 foot drifts of snow in our bare feet. AND WE LIKED IT.
And we didn't buy hamburgers at Mc Donalds...we would corner a cow in the pasture and... AND WE LIKED IT.
So, today, as yesterday, you can buy dedicated instrumentation amps, or you can roll your own. It just depends on what kind of cost/performance you are shooting for.
OK, I willMind you, I'm not taking sides on make vs buy.
You need to post a complete schematic, including how your signal source is connected, and your power supplies.Yet to resolve the linearity issue. I have connected the pin 5 to the ground which is my PSU's ground. I also tried connecting to "0" of input signal.Please help/
You have me baffled. How does grounding one input cause a bias current problem? How will a series resistor remedy that "problem"?It looks like you have grounded the inverting input. Not good!
Put a 10k resistor between the inverting input and ground. That should be enough to provide input bias current.
Can you post a photograph of your test setup?Yes I have gone through the datasheet.I have used a SMPS for powering the IC.I have connected all ground points( as shown in the schematic) to the powersupply common.Also I tried with R4 removed.
System works well for signal greater than 1 volt.(upto gain 5) I get excellent linearity.
Once when I connect with the signal level as shown in the schematic I get the following results.
Input signal Output Voltage
1mV 2V
2mV 3V
3mV 5V
4mV 6V
5mV 7V
These results are for gain 1000.
by Jake Hertz
by Duane Benson
by Jake Hertz