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Original question:

LM2904-Q1: The threshold for Vos.

LM2904-Q1: LM2904-Q1

JIE LIU
Prodigy 50 points
Part Number: LM2904-Q1
Other Parts Discussed in Thread: OPA2188-Q1, LT1013D, , OPA2991-Q1

Hi team,

In the TI application notes, it is introduced to adjust the Vos by DC feedback, but the specific operation method is not introduced. How to adjust the parameters of the DC feedback circuit to reduce the Vos of the amplifier?

Best Regards,

Ivy

  • 0
    Guru 247410 points

    In the first step, you calibrate the circuit by opening the switch and applying a known input signal (typically 0 V). The error at the output is then measured and stored somehow. Then, during normal operation, the measured offset is subtracted from the input signal. This is very much application specific; it is not possible to give a circuit that works in all circumstances.

    All this requires additional components (in particular, an error amplifier with lower offset) and design effort. The simplest and cheapest way to reduce the offset is to just replace the LM2904-Q1 with a better amplifier, e.g., OPA2991-Q1, LT1013D, or OPA2188-Q1.

    What is the actual problem you're trying to solve? What are the range of input voltages, output voltages, and frequencies, and the power supply voltage? What offset error can you afford?