Noise Analysis in Op Amp
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This document provides an overview of noise analysis in operational amplifier circuits. It discusses the main types of noise sources, including shot noise, thermal noise, flicker noise, burst noise and avalanche noise. It describes how to characterize noise using spectral density and equivalent input noise voltage. The document presents models for analyzing noise in inverting, noninverting and differential op amp circuits. It provides calculations for determining total output noise in different circuit configurations.
Noise Analysis in Op Amp
- 1. Noise Analysis in Operational Amplifier Circuits Source: Texas Instruments
- 2. Introduction Purpose This module provides information about the noise analysis in operational amplifier circuits Outline Provide an overview of the noise in operational amplifier circuits Discuss the types, characteristics and calculations of the noise Contents 22 pages Duration 10 Minutes
- 3. Overview Notational Conventions e and i indicate independent voltage and current noise sources; E and I indicate combinations or amplified versions of the independent sources. Spectral Density A spectral density is a noise voltage or noise current per root hertz, i.e. V/ √ Hz or A/ √ Hz . Spectral densities are commonly used to specify noise parameters. To avoid confusion in the following analyses, spectral densities are identified, when used, by stating them as volts or amps per root hertz.
- 4. Types of Noise In electrical circuits there are 5 common noise sources: Shot noise Shot noise is always associated with current flow. Shot noise results whenever charges cross a potential barrier, like a PN junction. Thermal noise Thermal noise is caused by the thermal agitation of charge carriers (electrons or holes) in a conductor. This noise is present in all passive resistive elements. Flicker noise Flicker noise is also called 1/f noise. It is present in all active devices and has various origins. Flicker noise is always associated with a dc current. Burst noise Burst noise, also called popcorn noise, appears to be related to imperfections in semiconductor material and heavy ion implants. Avalanche noise Avalanche noise is created when a pn junction is operated in the reverse breakdown mode.
- 6. Adding Noise Sources The result is :
- 8. Integrating Noise Equivalent Input Noise Voltage vs. Frequency for TLV2772 as Normally Presented Equivalent Input Noise Voltage vs. Frequency for TLV2772 on Log-Log Scale
- 9. Equivalent Noise Bandwidth Figure 1 : Figure 2 :
- 11. Op Amp Circuit Noise Model
- 12. Inverting and Noninverting Noise Analysis Circuit
- 13. Inverting and Noninverting Op Amp Circuit Noise Calculations
- 14. Inverting and Noninverting Op Amp Circuit Noise Calculations cont’d
- 15. Differential Op Amp Circuit Noise Model
- 16. Differential Op Amp Circuit Noise Calculations
- 17. Differential Op Amp Circuit Noise Calculations cont’d
- 18. Differential Op Amp Circuit Noise Calculations cont’d
- 19. Differential Op Amp Circuit Noise Calculations cont’d
- 20. Differential Op Amp Circuit Noise Calculations cont’d
- 21. Summary Noise is a purely random signal; the instantaneous value and/or phase of the waveform cannot be predicted at any time. Because noise adds by the square, when there is an order of magnitude or more difference in value, the lower value can be ignored with very little error. Noise is normally specified as spectral density in rms volts or amps per root Hertz, V/ √ Hz or A/ √ Hz . The instantaneous peak-to-peak value will be equal to or less than 6 times the rms value 99.7% of the time.
- 22. Additional Resource For ordering the amplifier products, please click the part list or call our sales hotline For additional inquires contact our technical service hotline For more information go to http://focus.ti.com/lit/an/slva043b/slva043b.pdf Newark Farnell