OPA1632: Clipping at low voltage

Vinicius PW

Part Number: OPA1632

Hello!

I'm using OPA1632 to amplify the signal coming from a microphone. As I'm only testing the circuit right now, the amplifier is configured with a gain of 2. I'm using +-12 supplies.

My problem is that the amplifier is clipping part o the signal at 1 V output.

Using a single ended input of 1,25 V at the non inverted input, I got this output (Vout+ in yellow, Vout- in blue):

My circuit is (R1 and R2 are 100k on the board):

I already used the same circuit in another board, with the difference that Vocm was not tied to GND, but to a CM voltage, and had no problem.

I would appreciate any help.

Thanks!

over 1 year ago

0 SimaJalaleddine over 1 year ago

TI__Mastermind 22280 points

Hello Vinicius,

With a +/-12V power supply configuration, tying Vcm to GND would give you the best results, as you have done.

Do you have +/-1.25V sin wave applied at the input of MicA0+ and JP1 populated?

Thank you,
Sima

0 Vinicius PW over 1 year ago in reply to SimaJalaleddine

Prodigy 75 points

Yes, this is my setup.

0 SimaJalaleddine over 1 year ago in reply to Vinicius PW

TI__Mastermind 22280 points

Hello Vinicius,

Thank you for the confirmation. I really don't see any issues with your circuit. I would recommend decreasing resistor values due to high valued resistors interacting with input impedance of amplifier + bias currents. But, this is not mandatory.

Are you probing right at the output of the amplifier with a low capacitance probe? Also are there any connections to Pot0OUT, Pot1Out, Pot0IN, and Pot1IN?

Thank you,

Sima

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OPA1632: Clipping at low voltage