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去看看 国外电子工业论坛上的 关于电子元器件说明中 有这样一段话：
Resistors
When voltage is applied to a resistor, it generally reduces in value in a non-linear fashion. When we first learned Ohm’s Law, we made the assumption that resistance was constant with applied voltage. That was a very good assumption. However, with high voltage applied, the change in resistance can be enough to result in a meaningful error. For example, some precision high voltage resistors have a voltage coefficient of 1 ppm/V, which initially looks small enough to be neglected. (Some HV resistor manufacturers even tout this as an excellent value.) A quick calculation shows otherwise. With, say, 20,000 volts across a resistor, the effect of VC caused the resistance value to change by 2%, which is quite a substantial linearity error when a precision measurement is needed. Thus, measuring a component’s resistance at low applied voltage is not sufficient when good accuracy and linearity is needed. One way to combat the effects of voltage coefficient is to use several resistors in series, thereby reducing the effect on each resistor, and the entire resistance string, in total.
The above discussion relates to actual resistors, designed to handle high voltages. Parasitic resistance of insulators can also affect a circuit. For example, an insulator can be a source of leakage current. The voltage coefficient of such a parasitic resistance can be orders of magnitude worse than an actual resistor, and in some precision applications can have a substantial adverse affect on circuit operation.
你明不明白 我给你圈红了的字 在说什么？ |
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发表于 2018-11-27 19:29
