What are clock tree types?

What are clock tree types?

There can be several structure for clock tree:

  • H-Tree.
  • X-Tree.
  • Multi level clock tree.
  • Fish bone.

What is clock tree generation?

When complexity (i.e. number of gates in a design) increase, the need to distribute clock signals in a controlled manner becomes more important. A large, pipelined chip may easily contain hundreds of clocked elements (latches, flip-flops, etc.), so it is obvious that a lot of buffering is needed.

What is clock root?

ICC uses the clock sources defined by the create_clock command as the clock roots and derives the default set of clock sinks by tracing through all cells in the transitive fanout of the clock roots. ICC will not synthesize a clock tree if its source is set to a constant value by using set_case_analysis.

What does a clock buffer do?

Clock buffer is typically used to fan out clock signal and isolate the source from the loads.

Why do we use a clock tree?

HFNS are used mostly for reset, scan enable and other static signals having high fan-outs. There is not stringent requirement of balancing & power reduction. Clock tree power is given special attention as it is a constantly switching signal.

Is clock skew good or bad?

Positive clock skews are good for fixing setup violations, but can cause hold violations. Negative clock skew can guard against a hold violation, but can cause a setup violation.

Why is it necessary to gating a clock?

Clock gating is a popular technique used in many synchronous circuits for reducing dynamic power dissipation, by removing the clock signal when the circuit is not in use. Clock gating saves power by pruning the clock tree, at the cost of adding more logic to a circuit.

What is free running clock?

Free-running sleep is a sleep pattern that is not adjusted (entrained) to the 24-hour cycle in nature nor to any artificial cycle. It occurs as the sleep disorder non-24-hour sleep-wake disorder or artificially as part of experiments used in the study of circadian and other rhythms in biology.

What is the difference between clock buffer and clock inverter?

To save area, the first buffer is typically of a lower drive strength and is placed very closed to the second inverter. The second inverter, however, is of higher drive strength. But for the second inverter, the load comprises of the wire cap as well as the input cap of the next buffer.

Why is clock skew bad?

Why clock signal is required?

Digital circuits. Most integrated circuits (ICs) of sufficient complexity use a clock signal in order to synchronize different parts of the circuit, cycling at a rate slower than the worst-case internal propagation delays. In some cases, more than one clock cycle is required to perform a predictable action.