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目前用分立元件组成的图像中频放大器都毫无例外地采用参差调谐(对双耦回路而言是参差阻尼)的办法来实现众所周知的幅度响应特性。为了设计方便,通常先设计一个低通原型网络,然后再转换至带通。这里可供选择的低通原型响应函数有三种:巴特沃斯响应函数(平顶型响应);贝塞尔响应函数(尖顶型响应);巴特沃斯——汤姆逊结合型响应函数(馒头型响应)。汤姆逊是贝塞尔响应函数的提出者,因此这种结合型响应函数实际上就是巴特沃斯——贝塞尔结合型响应函数,本文将对这三种响应函数的优、缺点作一比较和提供一个结合型响应的计算实例。并首先讨论一下实际的阶跃响应。
The currently used image IF amplifiers composed of discrete components all adopt the well-known tuned amplitude response characteristics by using the tuned tuning (which is a parametric damping for a double-coupled loop) without exception. For ease of design, it is common to first design a low-pass prototype network and then switch to bandpass. There are three types of low-pass prototype response functions to choose from: the Butterworth response function (flat top response); Bessel response function (spire response); Butterworth-Thomson combined response function (bread type response). Thomson is the proponent of Bezier’s response function, so this combined response function is actually the Butterworth-Bessel combination response function. In this paper, the advantages and disadvantages of these three response functions are compared And provide a concatenation of computational examples of responses. And first to discuss the actual step response.