OPA2211 Amplifier circuit output offset issue

Nilav,

Please show the details of your application by including circuit schematic with all the values of components,  supply voltage and input signal.

Hello Marek Lis,

My application is to amplify output of TX1 pin(3.3V, 1MHz signal) of  TDC1000-7200 EVM which is used for Ultrasonic water flow application and need to amplify 3.3V, 1MHz signal and getting offset at output even at 0V input at non inverting terminal. find attached image below.

Nilav,

Using 3.3V input signal in gain of 10 would require the output voltage to go to 33V which is not possible on Vcc of 12V.  Also, you do not specify what is the DC input voltage - the input common-mode voltage range of OPA211 for Vcc>10V (or >+/-5V) extends only from (V-)+1.8V to (V+)-1.4V - see dataseet table below; this means that for your single supply of 12V, the valid input voltage range is from 1.8V to 10.6V thus you cannot connect the input to DC ground and expect a valid output.

Hello Marek Lis,

I have initially tested with grounded of both IN+ and IN- signals to check offset problem and got offset of 1.9V(Oscilloscope image is attached in first post).

We actually working on circuit which was posted earlier,  Here Input V+ is 9V, V- is ground which is in common mode input range with gain 2 and output is 6.6V and still receive offset in output terminal so how can I remove offset from output?

Nilav,

You may NOT test the input offset voltage with the input grounded while using single supply because doing so violates the input common-mode voltage range; for more details please read or watch the Input/Output Limitation section of TI Precision Labs lectures under following link:

http://www.ti.com/lsds/ti/amplifiers-linear/precision-amplifier-precision-labs.page

If you want to measure the input offset voltage with the inputs grounded, you MUST use dual supplies so that 0V input is within the valid linear input range; that's how it is done in the datasheet - see below.

Is your input signal +/-1.65V (Vp=3.3V) or +/-3.3V (Vp=6.6V)?   The former will allow you to make the circuit work on single supply of 9V ONLY if you provide DC input of 4.5V (mid-supply) - in gain of 2 the output will be between 4.5+/-2*1.65V=1.2V & 7.8V but the circuit will NOT work with Vin_dc=0V nor with the input of +/-3.3V - see below.  

I also attached the circuit schematic so you may simulate it using TINA-TI software; you may download free simulator under following link: 

OPA211 circuit.TSC

Marek Lis,

Thank you for brief detail for offset.

My input is 3.3v p-p pulses(for non inverting config.) and getting this signal from TDC1000-7200 EVM (0 to 3.3V) and setting Vss=10V and getting offset in DC signal before pulses of 3.3v.

Nilev,

In single supply application, with Vss=10V, the valid input is defined from 2V to 8.6V - see datasheet input common-mode range below.  For that reason, what you measure with input grounded is NOT Vos but rather a meaningless results of the input stage operating in non-linear region.

Please watch the input/output limitation video under following link to understand the concept that the input and output voltage ranges are not absolute values but instead defined with respect to the supply rails used:

For Vss=10V, (V-)+2V < Vcm < (V+)-1.4V thus (0V+2V) < Vcm < (10V-1.4V) resulting in

 2V< Vcm < 8.6V

http://www.ti.com/lsds/ti/amplifiers-linear/precision-amplifier-precision-labs.page