LMV641: offset voltage

Lilian Chang

Part Number: LMV641

Hi Team,

Please help to review the schematic design of below circuit. Input is about 0.1V, 2X gain, tested at room temp. And my customer found the output offset is about 20mV, could it be anything wrong? 20mv if too much for my customer, do you have any suggestion? Thanks.

over 7 years ago

0 Errol Leon6 over 7 years ago

TI__Expert 5830 points

Hello Lilian Chang,

I have simulated the circuit in TINATI and have found that the reason for the offset is due to the input bias current of the LMV641. Reducing the resistor values will help reduce this offset, however, the capacitor values will have to change as well to have the desired filter response. Another option would be to have a lower Ibias part.

Best regards,

Errol Leon

Texas Instruments

Precision Amplifier Application Engineer

LMV641 Sallen Key Low-Pass Filter.TSC

0 Lilian Chang over 6 years ago in reply to Errol Leon6

TI__Intellectual 1555 points

Hi Leon,

I can't open your attached file, could you please help to give the plot of recommend design? Thank you.

0 Errol Leon6 over 6 years ago in reply to Lilian Chang

TI__Expert 5830 points

Hello Lilian Chang,

Do you have the all the specifications of the filter (desired cutoff frequency, load on the output, input signal, etc.)? I can then recommend a design and the appropriate amplifier.

Best regards,

Errol

0 Errol Leon6 over 6 years ago in reply to Lilian Chang

TI__Expert 5830 points

Hello Lilian,

I wanted to check in and see if you had the specification of the filter so I can recommend a design and proper op amp that meets there needs.
Could you confirm -3dB frequency they desire. The rest of the specifications I can get from the schematic.

Best regards,

Errol

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LMV641: offset voltage