SBOA570 may   2023 LMC6061 , LMC6081 , OPA192 , OPA2277 , OPA2350 , OPA277 , OPA320 , OPA328 , OPA350 , OPA391 , OPA392 , OPA4277 , OPA4350


  1.   Abstract
  2.   Trademarks
  3. Introduction
  4. Current Noise Versus Frequency
  5. How the SPICE Model Sets Current Noise
  6. Impact Current Noise has on a Non-inverting Amp With Large Source Impedance
  7. Impact of Current Noise has on the Transimpedance Configuration
  8. Current Noise Correlation
  9. Measuring Low Current Noise Levels
  10. Low Current Noise and Bias Current Considerations
  11. Summary
  12. 10References


This application note looks at how current noise impacts the total system noise, and when it is a concern. The emphasis is on low current circuits where current noise is less than 10fA/√Hz. This application note uses simulations and basic calculations to explain the role current noise, source impedance, and parasitic capacitance have on current noise. A simplified explanation describing the device level origin of the noise is also covered. Finally, methods used to measure this noise as well as practical board level precautions for current noise are covered.