翻訳と辞書 Words near each other ・ Half-pipe ・ Half-Pipe Hustle ・ Half-pipe skiing ・ Half-precision floating-point format ・ Half-proof ・ Half-Rate Honeymoon ・ Half-ration Névé ・ Half-reaction ・ Half-rubber ・ Half-Sack Epps ・ Half-side formula ・ Half-smoke ・ Half Pint Brawlers ・ Half Pints Brewing Company ・ Half Pipe (roller coaster) ・ Half power point ・ Half Price Books ・ Half range Fourier series ・ Half Rate ・ Half rhyme ・ Half sandwich compound ・ Half Serious ・ Half Shot at Sunrise ・ Half Shot Shooters ・ Half Smiles of the Decomposed ・ Half sovereign ・ Half sphere exposure ・ Half Thang ・ Half the Blood of Brooklyn ・ Half the Man Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Half power point ： ウィキペディア英語版 Half power point The half power point of an electronic amplifier stage is that frequency at which the output power has dropped to half of its mid-band value. That is a level of -3 dB. The half power point is a commonly used specific definition of cutoff frequency, although not the only one. This occurs when the output voltage has dropped by 1/√2 or 0.707 of the maximum output voltage (exact: $20\backslash log\_\backslash left(\backslash tfrac$) and the power has dropped by half (1/2 or 0.5) (exact: $10\backslash log\_\backslash left(\backslash tfrac\backslash right)\; \backslash approx\; -3.0103\backslash ,\; \backslash mathrm$). A bandpass amplifier will have 2 half power points, whilst a low pass amplifier will have only one. A high pass amplifier stage will have only the lower half power point. The bandwidth of an amplifier is usually defined as the difference between the lower and upper half power points. This is therefore also known as the −3 dB bandwidth. == 3 dB == The half power point is approximately 3 dB because $\backslash log\_\; 2\; =\; .3010...\; \backslash approx\; .3,$ so $10\; \backslash log\_\; 2\; =\; 3.010...\; \backslash approx\; 3;$ the decibel measure of a ratio ''r'' is defined as $10\; \backslash log\_\; r.$ Using 3 dB rather than the correct value of 3.010... yields a power factor of $G\; =\; 10^\backslash frac\; \backslash times\; 1\backslash \; =\; 1.99526...\; \backslash approx\; 2\; \backslash ,$ which differs from a factor of 2 by about 0.24%. As logarithmic errors add, using 6 dB to approximate a factor of 4 difference yields an error of about 0.48%, and so forth. This is the same mathematical coincidence as $2^\; =\; 1,024\; \backslash approx\; 1,000\; =\; 10^3$, which is the source of the ambiguity of the prefixes kilo-, mega-, etc. in a computing context. Taking the logarithm of both sides of the equation $2^\; \backslash approx\; 10^3$ yields $10\; \backslash log\_\; 2\; \backslash approx\; 3$. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Half power point」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.