本文所叙述的“数字频率合成的简易方法”是指用脉冲相加的办法来实现由一块晶体提供各种时钟频率的方法。这种方法能够按着需要迅速改变时钟频率,几乎不要求建立时间,这对实现快速多音频通讯很有用处。下面就介绍一下这种频率合成方法。一、“异-或”门数字混频。“异-或”门的逻辑表达式如下: A(?)B=AB+AB (1-1) 从表达式(1-1)可看出,“异-或”门是一个数字脉冲混频器。当经过“异-或”门的两列输入脉冲序列中的一列序列脉冲的前后沿与另一列序列脉冲的前沿或后 Described in this article, “a simple method of digital frequency synthesis” refers to the use of pulse addition to achieve a crystal provided by a variety of clock frequencies. This method quickly changes the clock frequency as needed, requiring very little settling time, which is useful for fast, multi-audio communication. Here's to introduce this method of frequency synthesis. First, “different - or” door digital mixing. The logical expression for the XOR gate is as follows: A (?) B = AB + AB (1-1) As can be seen from the expression (1-1), the XOR gate is a digital pulse mixing Device. When the fore and aft of one of the two series of input pulse trains passing through the exclusive OR gate coincide with the leading edge of the other series of pulse or