数字信号时序电路

时序电路简介 (Introduction to Sequential Circuits)

The word sequential circuit means "a circuit whose output depends on the order or timing of the inputs".

顺序电路一词的意思是“其输出取决于输入的顺序或时序的电路” 。

So, the sequential circuit consists of Y number of inputs, logic gates, and X number of outputs.

因此，时序电路由Y个输入，逻辑门和X个输出组成。

Sequential circuits produce output which depends upon current inputs and previous input variables. Thus, we can say that sequential circuits are capable of storing binary information. This binary information gives the state of the sequential circuit at that time. The block diagram of sequential circuits is given below,

顺序电路产生取决于当前输入和先前输入变量的输出。 因此，可以说顺序电路能够存储二进制信息。 该二进制信息给出了当时时序电路的状态。 时序电路的框图如下所示，

From the above figure, we can see that there are two types of input present. They are:

从上图中，我们可以看到存在两种类型的输入。 他们是：

1. External inputs which are not controlled by the circuit and do not depend on past input.

   不受电路控制且不依赖于过去输入的外部输入。

2. Internal inputs depend on past inputs.

   内部输入取决于过去的输入。

时序电路的类型 (Types of Sequential Circuits)

There are two types of sequential circuits which we study in digital electronics which are listed below,

下面列出了我们在数字电子学中研究的两种顺序电路，

1. Asynchronous sequential circuit

   异步时序电路

2. Synchronous sequential circuit

   同步时序电路

1)异步时序电路 (1) Asynchronous sequential circuit)

The asynchronous sequential circuit does not use a clock signal but they use the pulse of inputs. If we compare between Asynchronous sequential circuit and Synchronous sequential circuit, the Asynchronous sequential circuit has a clock pulse and it is capable of changing state immediately when there is a change in the input signal. Asynchronous sequential circuits are used where the speed of operation is important. It has a disadvantage that designing this circuit is difficult and output is uncertain.

异步时序电路不使用时钟信号，但使用输入脉冲。 如果我们在异步时序电路和同步时序电路之间进行比较，则异步时序电路具有一个时钟脉冲，并且能够在输入信号发生变化时立即更改状态。 在操作速度很重要的地方使用异步时序电路 。 缺点是设计该电路困难并且输出不确定。

2)同步时序电路 (2) Synchronous sequential circuit)

The synchronous sequential circuit uses clock signal and level inputs or pulsed inputs (which has a restriction on pulse width and circuit propagation). The output pulse takes the same duration as the clock pulse for the clocked sequential circuits. If we compare Synchronous sequential circuit and Asynchronous sequential circuit than Asynchronous sequential circuit is faster because in Synchronous sequential circuit they have to wait for the next clock pulse to arrive to perform the next operation, so Synchronous sequential circuit becomes a little bit slower. In this level of output change state happen at the starting of the input pulse and remain the same until the next clock pulse or input pulse come.

同步时序电路使用时钟信号和电平输入或脉冲输入(对脉冲宽度和电路传播有限制)。 输出脉冲与时钟时序电路的时钟脉冲持续时间相同。 如果我们比较同步时序电路和异步时序电路，则比异步时序电路要快，因为在同步时序电路中，它们必须等待下一个时钟脉冲到达才能执行下一个操作，因此同步时序电路会变慢一点。 在此级别的输出变化状态下，将在输入脉冲开始时发生这种情况，并保持不变，直到下一个时钟脉冲或输入脉冲出现为止。

They are used in flip flops and to design counters, registers, RAM, MOORE machines, and other state retaining machines.

它们用于触发器，并用于设计计数器，寄存器，RAM，MOORE机和其他状态保持机。

The block diagram of Asynchronous and Synchronous sequential circuits

异步和同步时序电路的框图

组合电路和顺序电路之间的区别 (Difference between Combinational Circuits and Sequential Circuit)

时序电路的应用 (Application of Sequential Circuits)

Sequential circuits are used at several places some of which are listed below:

顺序电路在几个地方使用，下面列出其中一些：

• They are applied in programmable devices, for example, CPLD (Complex Programmable Logic Device), PLD (Programmable Logic Device), and FPGA (Field Programmable Gate-Array).

  它们被应用于可编程设备，例如CPLD(复杂可编程逻辑设备)，PLD(可编程逻辑设备)和FPGA(现场可编程门阵列)。

• They are used as registers in microprocessors.

  它们用作微处理器中的寄存器。

• They are also used as controllers for storing temporary information.

  它们还用作存储临时信息的控制器。

• Shift registers, Flip – Flops, Clocks, Counters.

  移位寄存器，触发器–触发器，时钟，计数器。

• Conversion of analog signals to digital signals and vice-versa.

  模拟信号到数字信号的转换，反之亦然。

翻译自:

数字信号时序电路