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Reducing Op-Amp Output Noise from 12V DC Power Supply—Best Filtering Methods?

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  • #1 21674382
    Jitendra Kumar
    Anonymous  
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  • #2 21674383
    richard gabric
    Anonymous  
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  • #3 21674384
    Jitendra Kumar
    Anonymous  
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  • #4 21674385
    richard gabric
    Anonymous  
  • #5 21674386
    Jitendra Kumar
    Anonymous  
  • #6 21674387
    richard gabric
    Anonymous  
  • #7 21674388
    Sambath Kumar
    Anonymous  
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  • #8 21674389
    Sambath Kumar
    Anonymous  

Topic summary

The discussion addresses reducing output noise in an op-amp caused by noise from a DC power supply, specifically a 6 to 6.5 V supply with a current requirement of at least 80 mA. Key considerations include the noise frequency relative to the op-amp bandwidth, grounding quality, and the type of power supply (linear vs. switch mode). The OPA847 op-amp from Texas Instruments, with a typical supply current of 18.1 mA, is used, and the user seeks to increase current delivery while minimizing noise. Recommendations emphasize avoiding series resistance in the power supply line to maintain low impedance, using linear regulators or low-dropout (LDO) regulators with good power supply rejection ratio (PSRR), and implementing LC or Pi filters with low equivalent series resistance (ESR) capacitors. Proper PCB layout, power supply decoupling, and feedback network design are critical due to the high-speed nature of the OPA847. Additional suggestions include using a 7805 voltage regulator to supply 5 V, adjusting resistor values in the filter circuit, and employing earth loop resistors to suppress ground noise. Demonstration boards from Texas Instruments and careful schematic design are advised for stability and noise reduction.
Summary generated by the language model.
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