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LMV324A: Differences between LMV324A and LMV324

?? ??
Prodigy 10 points
Part Number: LMV324A
Other Parts Discussed in Thread: LMV324,

Tool/software:

I am using a bandpass filter and a lowpass filter using an op-amp.
Until now I have used the LMV324, but this time I used the LMV324A.
There was a difference in the amplitude (peak to peak) of the waveform after passing through the bandpass filter and the lowpass filter.
Which characteristic of the op-amp causes this difference?
When I looked at the datasheet, there was a difference in the slew rate, but is this characteristic the cause?

(Reference) Measurement results
LMV324: 2.4V
LMV324A: 2.7V

(Reference) Slew rate
LMV324: 1.0V/us
LMV324A: 1.7V/us

  • 0
    Guru 273570 points

    The LMV324 is a bipolar device; the LMV234A is a more modern CMOS device.

    The most important differences are the common-mode range (the LMV324A works better for high input voltages) and the input bias current.
    Please show the schematic, and specifiy the actual input voltage range.

  • 0 in reply to Clemens Ladisch
    TI__Guru*** 146316 points

    Hello, welcome to the e2e forums.

    Based on the filter design and input signal, which output (if any) is the one that a perfect op amp would produce?

    Other than amplitude was there any other difference in the waveform?

  • 0
    Prodigy 10 points

    Hello

    I will share the circuit diagram and the measured waveforms.

    Thank you in advance.

  • 0 in reply to ?? ??
    Guru 273570 points

    Please check the IN− waveforms of both opamps. Do they deviate from 0.581 V for either LMV324 or LMV3245A?

  • +1 in reply to Clemens Ladisch
    TI__Guru*** 146316 points

    ?? ??,

    Do you want your circuit to distort the input signal in a specific way?

    A perfect op amp would not distort the signal.

    For a perfect op amp, the output of both amplifiers would have a negative voltage peak. LMV324 can't do that with signal supply

    The amount of time stuck at VOL (overload recovery) and the rate that op amps return to linear operation (slew rate) varies with op amp speed.

    In other words the results are a combination of passive components and op amp parameters. Well deigned op amp circuits only depend on combination of passive components for desired result. 

  • 0 in reply to Ron Michallick
    Prodigy 10 points

    Hello.
    Thank you for your reply.
    I found out that to get the same results as the circuit using LMV324, I need to adjust the passive components to match LMV324A.