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Original question:

THS3121: New and alternative OPAMP parts

OPA192: Replacment for LT1028

d_zero
Genius 5055 points

Part Number: OPA192
Other Parts Discussed in Thread: OPA2675, OPA1678, OPA2189, OPA2375, OPA2182, OPA2192, OPA211

Dear Team,

 

Case1)

please can you propose a replacment for LT1028 in regards to the output voltage noise?

In orginal desing the LT1028 is followed by LT1210 to support curretn spikes ( we will repleace the LT1210 with OPA2675)

Both LT1028 and LT1210 are confugured in unity gain configuration and are supplied with +4V and -3.3V, but we can also use +5V/-5V or +2.5V/-2.5V as we need to supply a -0.7V BIAS, I can share more info in DM.

Case2)

We need to generate a low noise BIAS of 3.5V ( Average cuurent 1mA) and ripple < 30uVpp, voltage of the opamp +5.2V / 0V

-----------------------------

i did some sorting and OPA1678, OPA2375, OPA2189, OPA2182 and OPA2192 looks promising, 

 

Please let me know your toughts.

 

Best Regards,

d.

  • 0
    TI__Mastermind 29298 points

    D,

    1. The closest device to the LT1028 is OPA211.  Both devices have similar noise specifications (about 1.1nV/rtHz at 1kHz), and both have similar bandwidth.   
    2. It may be that you do not need the ultra low broadband noise.  The OPA1678, OPA2375, OPA2189, OPA2182 and OPA2192 are all low noise devices, but they are not as low as OPA211.  It sounds to me like you are trying to generate a low noise DC bias voltage.  Since it is DC you may want to use a device like OPA2189.  This op amp has very good DC accuracy, and no flicker noise.  The total peak-to-peak noise you get at the output of an op amp is related to the noise density and the bandwidth.  A low noise device like OPA211 is a great option if you really need 45MHz of bandwidth, but if you are generating a DC bias point you don't need 45MHz.  If you limit with a filter the bandwidth a device like OPA2189 is a good option because it doesn't have 1/f noise.
    3. I can comment better if you show me your schematic.  If you just want a pin for pin OPA211 is very similar.  With both the LT1028 and the OPA211 you should pay attention to your input and output ranges. Both devices have limited ranges on a single supply.  I can check this with a schematic.

    Best regards, Art

  • 0 in reply to Art Kay
    Genius 5055 points

    Dear Art,

    thank you for the feedback, i sent you a DM with more details.

    Best Regards,

    d.