A question about critical path, thanks!

[birdxpe]

what is critical path?
for combinationa logic, is it the path whith the largest delay from input to output ?
for sequential logi, suppose the circuit is composed of clock,reset,FF,and combinational logic between FFs, where is the critical path's start point and where is end point?
thanks very much

 

[sinwave]

From active clock edge to FF output, through combo logic, to the D input of next FF, plus setup time.

 

[semiconductorman]

there are several endpoints that need to be considered
1. input - output ( purely combinational ckt)
2. input - flipflop input
3. flipflop output to chip output
4. flop input to next flop input
5. clk input to next flop inpt

 

[buzkiller]

Critical path

A signal in a section of combinatorial logic that limits the speed of the logic. Storage elements begin and end a critical path.


The path within a design that dictates the fastest time at which an entire design can run. This path runs from the source to a sink node such that if any activity on the path is delayed by an amount t, then the entire circuit function is delayed by time t.