VLSI SoC Design: Concepts, Perspective & Implementation
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April 24, 2018
False path v/s case analysis v/s disable timing.
- Some latest tool versions also support a case value of static which means that the node will always be static (never toggle), and this is used to reduce the pessimism which doing noise analysis.
- Case analysis is also particularly useful for DFT modes where you would want to set a few configuration registers and drive the chip into a particular DFT mode: like atspeed, shift or stuck-at mode. This acts as an additional level of verification because you'd expect to see only scan chains in the shift mode with scan enable being 1. You'd expect to see functional paths in the atspeed mode with scan enable being X, and you'd expect to see only paths ending at functional register inputs in the stuck-at mode with scan enable being 0.
What does it mean when you say "For example if you have a MUX based divider"? What sort of divider are you talking about? Please reply
Hi Naman, In first example , lets name the flop below flop B as H. Now is there any valid timing path between flop H and flop G?
So does this mean that in all the 3 cases above,the tool will fix or try to fix max cap, max fanout and max slope?
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VLSI Physical Design
Monday, october 5, 2015, case analysis and mode analysis.
Hi, Can you add more information about how can you implement this with PrimeTime? So I understand that I have to use some input ports to configure them with mode that I want to run, but in this case those ports are not analysed?
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Wednesday, April 28, 2021
Static timing analysis based on operating conditions, type of analysis based on operating conditions.
- Single Operating Condition Mode
- Min-Max (Bc_wc) Operating Condition Mode
- On_chip_variation Mode
- No CRPR – Means we are not going to remove any Clock Reconvergence Pessimism. (Please read CRPR from my POST http://www.vlsi-expert.com/2011/02/clock-reconvergence-pessimism-crp-basic.html )
- Zero Net Delay
- No other clock related uncertainty. 😊
- Doing only Single cycle Analysis
- I have just mentioned the delay values directly as per the circuit but actually tool is going to calculate the delay value based on Transition time and output Load. To understand that part please refer my other articles.
- Setup and Hold Time also have dependency on type of waveform at D2 pin but right now just making it simple. 😊
Single Operating Mode:
- I have picked Rise Buffer delay in both cases, Why?
- I have used Clock2Q delay is for falling waveform at Q1 even though Rising waveform Delay at Q1 is more then falling waveform delay at Q1, Why?
Min_Max (Bc_Wc) Operating Mode:
On-chip-variation analysis mode:.
- OCV mode is more closure toward the real scenario –
- If you fix setup slack in this mode – it will fix in other mode of analysis also.
- If there is no Hold Violation in this mode – it will not be in other 2 also
Must Read Article
The curious case of ‘interface analysis’!!
This is an important part of static timing analysis,
Case 1 : c2q and combinational delay for the input side is known, as shown below.
Case 2 : Input ‘in’ is stable ‘x’ ps before clock rising edge and ‘y’ ps after clock rising edge
Case 4 : Output ‘out’ is stable ‘x’ ps before clock rising edge and ‘y’ ps after clock rising edge
Case 5 : Data can change within a window of ‘x’ ps before clock edge and ‘y’ ps after same clock edge (source synchronous interfaces)
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CASE ANALYSIS: Using set_case_analysis, any node can be constrained to a boolean logic value of 1 or 0. All case values are evaluated and
Typically , you analyze the timing for each mode seperately. To place the design into a specific operating mode, you can use a technique called
The case analysis command is commonly used to describe a functional mode in the design by setting constants in the logic like what configuration registers
Specifies that a port or pin is at a constant logic value 1 or 0. Case analysis is a way to specify a given mode of the design without altering the netlist
BC_WC Operating condition Analysis mode – it's known as Best case Worst Case operating mode. It means we are going to use 2 extreme set of delay
The curious case of 'interface analysis'!! Hello. This is an important part of static timing analysis,. Below is the link:.
In this paper, we present a new approach for realistic worst-case analysis of VLSI circuit performances and a novel methodology for circuit performance
Static Timing Analysis (STA). • STA checks the worst case propagation of all possible vectors for min/max delays. • Advantages:.
Case Analysis. ○ Multiple Clocks per Register. ○ Minimum Pulse Width Checks. ○ Derived Clocks. ○ Clock Gating Checks. ○ Netlist Editing.
Digital worst-case timing analysis (WCTA) analyzes the timing of digital devices under worst-case end-of-life conditions including initial