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OPA2171: OPA2171 Application and Spec Question

Wen Yung
Expert 1220 points
Part Number: OPA2171
Other Parts Discussed in Thread: LM2904, TLV2314, TLV2316, TLV2171, OPA2314, OPA2316

Hi Sir,

Currently my customer survey OPA2171 now. But have some question need you help.
Application Audio ECM Signal end to Differential.

ECM Differential Circuit (083016').pptx

Spec as below:
1. meet AEC-Q100 (base on cost issue, Q100 also not require need)
2. Operator Voltage : 3VDCmin
3. noise < 40nV/rtHz @1kHz (Relatively LM2904, currently Noise Floor need improve 18dBA)
4. PSRR >> 65dB
5. PSR << -95dBV(A)
if OK, could you help provide formula unit about nV/rtHz translate to dB ?


 

  • 0
    TI__Genius 15410 points

    Hello,

    I believe the OPA2171 will meet all of the specifications you are looking for. Below I show the specifications of the OPA2171 that you mentioned you are concerned about in your post.

    Minimum Supply Voltage: 2.7V
    Noise Density @ 1kHz: 14nV/rt-Hz
    PSRR: 65dB @ ~2kHz

    You could also take a look at the TLV2314, TLV2316, OPA2314, OPA2316, or the TLV2171 for other amplifier options.

    To convert from nV/rt-Hz to dB, you will need to know the magnitude of your signal and the overal noise of your circuit. This will allow you to calculate the Signal to Noise Ratio (SNR). SNR = 20*log(signal magnitude in units of volts RMS/system noise in units of volts RMS).

    I recommend watching our TI Precision Lab videos on Noise to help in calculating the overall noise of your circuit.

    I also recommend reading our Single Supply, Electret Microphone Pre-Amplifier Reference Design which will show how to perform calculations and simulations for noise to eventually calculate the overall SNR of the system.

    Thank you,

    Tim Claycomb