Topics
Characteristics of Thin Film
Resistors ;
Low Noise and Low Distortion
1.Current noise generated in the resistor
The major noise generated inside the resistor is the noise generated in the discontinuous part of the material. The material structure of a thick film resistor is a fired mixture of conductive particles and insulating glass. Current (electron) flows to the point where conductive particles are connected. When an electric current (electron) passes through a contact point of a particle, a physical change occurs at the contact point accompanied by the generation of heat, resulting in a change in the current flowing. This is equivalent to a subtle change in resistivity and appears as noise. Furthermore, although resistors convert electric power into heat due to their nature, thermal expansion and contraction affect the contact points between particles and appear as thermal noise.
Thin film resistors differ from thick film resistors in that the material structure is metal-to-metal coupling, and current (electron) flows through the crystal lattice of the metal-to-metal coupling. There is no discontinuous contact of the material, and there is no noise caused by this. Therefore, the noise of the thin film resistor is very low regardless of the ambient temperature.
2.Third harmonic distortion
The third harmonic distortion (linearity of the resistor) is a property closely related to the noise generated in the resistor. An ideal resistor has voltage-current characteristics according to Ohm's law, but an actual resistor shows a slight non-linearity. This is because when a sinusoidal voltage is applied to the resistor, an electromotive force generated inside the resistor causes distortion that is not partially proportional to the current and voltage. This distortion can be resolved as a harmonic component of the applied sine wave. The third harmonic distortion (third harmonic distortion) is defined as the third harmonic distortion, which appears as the largest value among them.
The current distortion occurs at the junction of the different conductors, and the fluctuation of the current including the thermoelectromotive force generated when the current flows becomes one element of the noise. The greater the current fluctuation, the worse the linearity and the greater the third harmonic distortion. The third harmonic distortion is used as a method to detect the imperfection of the connection at the connection part of the dissimilar conductor or the metallic foreign matter which electrically contacted on the resistor.
Electron Flow in Thin Film Resistors
Low distortion due to the smooth flow of electrons between the electrode film and the resistive film formed continuously in a pure vacuum
Electron Flow in Thick Film Resistors
The distortion generation due to electron
disturbance caused by numerous point contacts
between metal particles and dielectric materials in
thick film materials.
The distortion at the boundary between non-ohmic
electrode and resistive materials
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