How many types of isolation cells are there?

In previous post, we discussed why isolation cells are required in low power design. Let’s look at the types of isolation cells available in low power design.

1. Isolation cell with clamp_value 1: In isolation mode, this cell drives 1 to its downstream logic. In normal mode, it acts as a buffer. This is similar to OR gate.
2. Isolation cell with clamp_value 0: In isolation mode, this cell drives 0 to its downstream logic. In normal mode, it acts as a buffer. This is similar to AND gate.
3. Latch type Isolation cell: In isolation mode, this cell will keep the latched value and drive its downstream logic. In normal mode it acts as a buffer. This is similar to Latch.
4. Enable Level Shifter cell: This type of Isolation cells can perform both level-shifting and isolation functions. It is used where a signal crosses from one power domain to another, where the two voltage levels are different and the first domain can be powered down.