- #1
amaresh92
- 163
- 0
I wonder if anyone could tell me how and why the noise is created by the any electronic circuit or clipping circuit?
thanks
thanks
Click For Summary
Discussion Overview
The discussion revolves around the causes and characteristics of noise in electronic circuits, including clipping circuits. Participants explore the nature of noise, its origins, and its implications in circuit behavior, touching on both theoretical and practical aspects.
Discussion Character
- Exploratory
- Technical explanation
- Conceptual clarification
- Debate/contested
Main Points Raised
- One participant inquires about the mechanisms behind noise creation in electronic circuits, particularly in clipping circuits.
- Another participant explains that noise arises from the inherent movement of electrons in response to ambient conditions, which adds to the input signal in a circuit.
- A different participant notes that clipping a sine wave introduces higher frequency harmonics, which can contribute to noise in the circuit, distinguishing it from random or thermal noise.
- One participant references the Johnson-Nyquist equation as a theoretical limit for noise in electronic circuits, mentioning the role of the Boltzmann constant and amplifier noise figures in determining total circuit noise.
Areas of Agreement / Disagreement
Participants present various perspectives on the nature and sources of noise, with no consensus reached on a singular explanation or model. Multiple competing views regarding the types of noise and their origins remain evident.
Contextual Notes
The discussion includes references to specific equations and concepts, such as the Johnson-Nyquist noise, but does not resolve the implications of these theories in practical scenarios. Assumptions regarding ambient conditions and their effects on electron movement are not fully explored.
Who May Find This Useful
This discussion may be of interest to those studying electronics, circuit design, or noise analysis in engineering contexts.
- #2
chaoseverlasting
- 1,051
- 3
Why does any electronic circuit function? The underlying form of energy is electrical. Electrical energy may be represented by movement of electrons. When a particular signal passes through a circuit, it causes the electrons present in the devices of that circuit (R, L, C) to move in a certain way.
However, the movement of electrons in a device is also affeced by ambient conditions (temperature primarily). These conditions give the electrons present in the device some inherent energy (kinetic energy). As these electrons are already moving in a certain way, the signal reproduced at the output of the circuit is the additive sum of the input signal plus the inherent movement of the electrons. We call this inherent movement 'noise'.
However, the movement of electrons in a device is also affeced by ambient conditions (temperature primarily). These conditions give the electrons present in the device some inherent energy (kinetic energy). As these electrons are already moving in a certain way, the signal reproduced at the output of the circuit is the additive sum of the input signal plus the inherent movement of the electrons. We call this inherent movement 'noise'.
- #3
dlgoff
Science Advisor
Gold Member
- 4,458
- 3,265
Clipping a sine wave results in higher frequency harmonics. These extra frequencies can get into your circuit and is called "noise" albeit not like the random/thermal noise that chaoseverlasting mentioned.
Here the extra frequencies due to clipping are odd harmonics; hence the 3,5,&7.
http://hyperphysics.phy-astr.gsu.edu/hbase/audio/amp.html"
Here the extra frequencies due to clipping are odd harmonics; hence the 3,5,&7.
http://hyperphysics.phy-astr.gsu.edu/hbase/audio/amp.html"
Last edited by a moderator:
- #4
Bob S
- 4,662
- 8
The lower noise limit in an electronic circuit is given by the Johnson-Nyquist equation
http://en.wikipedia.org/wiki/Johnson–Nyquist_noise
where kB is the Boltzmann constant 1.38 x 10-23 Joules per degree Kelvin.
In addition, there is an amplifier "noise figure", representing amplifier input noise, to be added to the total circuit noise, referenced to the input.
Very nominally, the noise limit is ~ -114 dBm per MHz.
[added note]
kBT = 1.38 x 10-23 x 106 x 293 = 4.04 x 10-12 milliwatts per MHz.
10 Log (4.04 x 10-12) = -113.9 dBm per MHz
Bob S
http://en.wikipedia.org/wiki/Johnson–Nyquist_noise
where kB is the Boltzmann constant 1.38 x 10-23 Joules per degree Kelvin.
In addition, there is an amplifier "noise figure", representing amplifier input noise, to be added to the total circuit noise, referenced to the input.
Very nominally, the noise limit is ~ -114 dBm per MHz.
[added note]
kBT = 1.38 x 10-23 x 106 x 293 = 4.04 x 10-12 milliwatts per MHz.
10 Log (4.04 x 10-12) = -113.9 dBm per MHz
Bob S
Last edited:
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