Model analysis of establishment time and holding time

Build time and hold time model analysis

The starting point is the source trigger D1 Sampling time of , The destination is the destination trigger D2 Sampling time of , It is assumed that the starting point has met the requirements of establishment time and holding time , Now analyze whether the end-point sampling time also meets the requirements .

among

• Tco： The data is sampled correctly from D End arrival Q The delay of the end , Trigger intrinsic properties , It can't be changed .
• TDelay：D1 Output to D2 Combinational logic delay and wiring delay at the input .
• Tsu： Trigger setup time , Inherent properties of triggers , It can't be changed .
• Th： Hold time of trigger , Inherent properties of triggers , It can't be changed .
• Tclk： Clock cycle .
• t1： Assume that the source clock is clka,clka arrive D1 Time delay of .
• t2：clka arrive D2 Time delay of .

The behavior of triggers ： Sampling data when the clock edge arrives D, Deposit the collected data , And output to the Q End , All if no new clock comes along , be Q The output of the terminal is always the last sampled data , Every clock edge , Sample the data once D.

hypothesis clk There is no delay in transmission ： Then the rising edge of each clock will arrive at the same time D1 and D2. The beginning of time , The first clock edge D1 Sampling time of , The end of time , The second clock edge D2 Sampling time of . Physical starting point ,D1 The input end of the , Physical end point ,D2 The input end of the .

Set up time to meet （ Focus on data headers ）： When the first clock comes , data data From the starting point ① Start transmitting , after Tco arrive ②, after TDelay