Setup/Hold Time Problem Danny Mok Altera HK FAE (amok@altera.com) bBRA Copyright 1997 Altera Corporation 9/12/97
Copyright © 1997 Altera Corporation 9/12/97 Setup/Hold Time Problem Danny Mok Altera HK FAE (dmok@altera.com)
Example 1 DF d吕 OUTPU↑ q1 Name Value 6.4ns 128ns d1 clk1 Is the design simple enough to course any error? Any Setup/Hold time problem? Copyright 1997 Altera Corporation 9/12/97
Copyright © 1997 Altera Corporation 9/12/97 Example 1 Is the design simple enough to course any error ? Any Setup/Hold time problem?
Let us take a look L Simulator: Timing simulation 区 Simulation *i Messages. Simulator murato warning: Found hold time violation at 14. Ons on register: 1. 0 Start Timewarning: Found setup time violation at 18. 6ns on register 1.Q 厂 Use de v Setup/H Sta Rememb! Message 0 of 2 Locate in floorplan Editor Help on Message check op Locate >0 of0 L往(e What? I get Setup/ Hold time problem? Copyright 1997 Altera Corporation 9/12/97
Copyright © 1997 Altera Corporation 9/12/97 Let us take a look Remember to turn on this Setup/Hold time check option What ? I get Setup/Hold time problem ?
oK What can i do Look at the Setup/Hold time Matrix from the Timing Analysis □区 Setup/Hold Time Analysis Setup time=2.2ns Clocks Hold time =0.7ns clk1 2.2ns/0.7ns nput Start Stop List Paths Copyright 1997 Altera Corporation 9/12/97
Copyright © 1997 Altera Corporation 9/12/97 OK, What can I do ? Look at the Setup/Hold time Matrix from the Timing Analysis Setup time = 2.2ns Hold time = 0.7ns
My Waveform Input Name 6.4ns 12.8ns Setup time= 2ns Hold time =0.Ins According to Setup/Hold Matrix How to fix Setup time needs=2.2ns It is easy. Extend the Setup time from 2ns to 2.2ns Hold time needs=0.7ns Extend the hold time from 0.Ins to 0.7ns bBRA Copyright 1997 Altera Corporation 9/12/97
Copyright © 1997 Altera Corporation 9/12/97 My Waveform Input Setup time = 2ns Hold time = 0.1ns According to Setup/Hold Matrix Setup time needs = 2.2ns Hold time needs = 0.7ns How to fix ? It is easy. Extend the Setup time from 2ns to 2.2ns Extend the Hold time from 0.1ns to 0.7ns