分立晶体管与TTL门电路的饱和输出状态的比较分析*

在高校的《数字电路》课程教学中,通常要对分立NPN晶体管和TTL门电路的低电平输出近饱和、饱和以及退饱和状态进行讲解,其中出现了貌似矛盾的现象。本文给出了两种情况下的比较分析,力图廓清对它们模棱两可的理解,并尝试给出了“被动饱和”与“主动饱和”两个新概念,建议了更为合理的饱和深度的定量表达式,以期对相关的教学以及教材编写起到积极的作用。

Comparative Analysis on the Saturation Output States of a Discrete Transistor and a TTL Gate Circuit

In the teaching process of "Digital Circuit" in colleges and universities, it is common to explain the near-saturation, saturation and de-saturation of the low-level outputs of a discrete NPN transistor and a TTL gate circuit, and there seems to be seemingly contradictory phenomena. This paper gives a comparative analysis of the two cases, trying to clarify their fuzzy understanding. Furthermore, we try to give two new concepts of "passive saturation" and "active saturation", and suggest a more reasonable quantitative expression of the saturation depth. This paper is expected to play a positive role in the teaching of the related electronic technology basic courses and in the preparation of teaching materials.