INA1620: DC Offset removal for INA1620

Jahongir Dodokhonov

Part Number: INA1620
Other Parts Discussed in Thread: OPA1622

Hi TI Support Team,

I have an issue related with DC Offset at the output of INA1620 amplifier. DC offset measures at 25-50 mVolts, when the volume of device was at half of its possible maximum level.

INA1620 amplifier is configured according to the schematic shown below. The signal from analogue out of active LPF goes to IN+ inputs of INA1620 and IN- are left floating.

Could you please explain what could be wrong with the INA1620 connection that I measure this amoung of DC affset at its outputs?

As I understood the INA1620 is based on OPA1622 typology and I tried it many time on different devices like mp3 players based on active LPF as shown below and had no issue with such a big DC offset values at its outputs.

Regards,

over 3 years ago

0 Jahongir Dodokhonov over 3 years ago

Prodigy 130 points

0 Iwata Etsuji over 3 years ago in reply to Jahongir Dodokhonov

TI__Expert 6380 points

Hello, Jahongir,

Could you please tell us the supply voltage condition for this application?
Because the supply voltage is related to the input/output range limitation and sometime cause an unexpected behavior such as offset.

Best regards,
Iwata Etsuji

0 Jahongir Dodokhonov over 3 years ago in reply to Iwata Etsuji

Prodigy 130 points

Hi Iwata,

The INA1620 is supplied by bipolar power supply set at voltage 11 volts for each supply rails.

I also would like to mention that each opamp power supply is isolated with ferrite bead. So I have a common power supply for active LPF opamp and INA1620 and they are isolated from each other with ferrite beads.

Could these ferrite beads cause some kind of ossilation leading to an unexpected behavior such as offset?

Regards,

Amplifiers

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INA1620: DC Offset removal for INA1620