Flip-flops
Table of contents
Introduction
You covered about latches in the previous modules. Those are the basic building blocks of flip-flops. You can implement flip-flops in two methods.
In first method, cascade two latches in such a way that the first latch is enabled for every positive clock pulse and second latch is enabled for every negative clock pulse. So that the combination of these two latches become a flip-flop.
In second module, you can directly implement the flip-flop, which is edge sensitive. In this module, let us discuss the following flip-flops using second method.
Differences between latches and flip-flops
| Latches | Flip-flops |
|---|---|
| Level triggered | Edge triggered |
| Asynchronous device | Synchronous device |
| Doesn’t contain clock signal | Contains a clock signal |
| It will change its state as long as it is enabled | It will change its state only during a given clock cycle |
| Consumes less power | Consumes more power |
| Faster | Slower |
| Examples: D-Latch, T-Latch | Examples: D-Flip flop, T-Flop flop |
Sub-modules
Now let us implement various flip-flops by providing the cross coupling between NOR gates. You can also implement these flip-flops by using NAND gates, as well.