IEC 60195 pdf download

IEC 60195 pdf download.Method of measurement of current noise generated in fixed resistors
1 Scope
This International Standard specifies a method of measurement and associated test conditions to assess the “noisiness”, or magnitude of current noise, generated in fixed resistors of any given type. The method applies to all classes of fixed resistors. The aim is to provide comparable results for the determination of the suitability of resistors for use in electronic circuits having critical noise requirements. The current noise in resistive materials reflects the granular structure of the resistive material. For some resistor technologies utilizing homogenous layers it is regarded as providing an indication of defects, which are considered as a root cause for abnormal ageing of the component under the influence of temperature and time. The method described in this International Standard is not a general specification requirement and therefore is applied if prescribed by a relevant component specification, or, if agreed between a customer and a manufacturer.
3 Terms and definitions
For the purposes of this document the following terms and definitions apply. 3.1 current-noise combination of all random fluctuations of current flow in a resistor which are not attributed to thermal agitation of the charge carriers (thermal noise) and which depend on the applied direct current 3.2 current-noise index A 1 logarithmic index of the ratio of the open circuit r.m.s. current-noise voltage in a frequency decade, in µV, over the d.c. voltage applied under test, in V, used to express the “noisiness” of an individual resistor Note 1 to entry: The current-noise index is expressed in dB. The ratio between µV and V is not considered in this index, leading to its value being 1 20 dB less than the mathematical current-noise index A 1 ′. This practical index follows the history of prior revisions of this method.3.3 mathematical current-noise index A 1 ′ logarithmic index of the ratio of the open circuit r.m.s. current-noise voltage in a frequency decade over the d.c. voltage applied under test, established in consistent units and their multiples Note 1 to entry: The mathematical current-noise index is expressed in dB. This index has been introduced for the mathematical derivation of the considered parameters. 3.4 current-noise voltage ratio CNR U ratio of the open circuit r.m.s. current-noise voltage in a frequency decade over the d.c. voltage applied under test, established in µV/V, used to express the “noisiness” of an individual resistor 3.5 flicker noise pink noise random fluctuation present in most electronic devices and typically related to internal properties of the respective device, which depends on direct current and has a power spectral density inversely proportional to the frequency 3.6 noise random fluctuation in an electrical signal having instantaneous amplitude values which, due to their distribution in a random manner, can only be predicted in terms of probability statements 3.7 shot noise random fluctuation in electric current due to the flowing current consisting of discrete charges, which is independent of temperature and has nearly constant power spectral density throughout the frequency spectrum 3.8 thermal noise random fluctuation generated by the thermal agitation of the charge carriers (usually the electrons) inside an electrical conductor at equilibrium, which is independent of any applied voltage and has nearly constant power spectral density throughout the frequency spectrum Note 1 to entry: Thermal noise is also referred to as Johnson noise or as Nyquist noise.
4 Method of measurement
4.1 Noise basics 4.1 .1 Noise Noise appears as a spontaneous fluctuating voltage e n ( t ) with instantaneous amplitude values. Noise voltage is a statistically independent random variable, where for most kinds of noise the frequency distribution of amplitudes follows a Gaussian distribution curve. Therefore noise voltage cannot be predicted except in terms of probability statements. Usually the characteristic of principal interest is not the instantaneous amplitude value but the “time-averaged” value.