“什么是晶体管的截止频率?”这是一个经常可以听到的问题.在本文中将对常见的f_α、f_β、f_1、f_T、f_(os??)等符号简要地加以解释. f_α这是共基极接法的截止频率.低频时,电流放大系数α几乎等于1;当频率升高,α下降到相当于低频时的1/2~(1/2)倍时,这时的频率称为α截止频率即f_α,也就是半功率或3分贝频率.用于声频的晶体管,f_α一般是500千赫;用于射频的晶体管,f_α可高达300兆赫. f_β这是共发射极接法的截止频率.共发射极是 “What is the cut-off frequency of a transistor?” This is a frequently-seen problem, and the common notations such as f_α, f_β, f_1, f_T, f_ (os ??), etc., are briefly explained in this article. Common base connection of the cut-off frequency. At low frequencies, the current amplification factor α is almost equal to 1; when the frequency increases, α down to the equivalent of 1/2 ~ (1/2) times the low frequency, then the frequency Is the alpha cutoff frequency, f_α, that is, half-power or 3-decibel frequency. The transistor used for audio, f_α is typically 500 kHz; the transistor used for radio frequency, f_α can be as high as 300 MHz f_β This is a common emitter connection Cutoff frequency