Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

details about OCV and AOCV

Status
Not open for further replies.

cyrax747

Full Member level 3
Joined
Nov 8, 2012
Messages
169
Helped
13
Reputation
26
Reaction score
11
Trophy points
1,298
Location
Bangalore
Activity points
2,485
Hi All,

Can you please help me in understanding OCV and AOCV and its application in static timing analysis.
 

shobhit

Member level 2
Joined
Oct 4, 2007
Messages
49
Helped
13
Reputation
26
Reaction score
10
Trophy points
1,288
Location
India
Activity points
1,643
OCV: On chip Variation of Voltage, temperature, Process.
When a chip is fabricated, it is present with other identical chips on the wafer. There are some variations which happen on the complete wafer, these are referred to as global variations, and the variations which happen on the chip only are said to be OCV. We need to take care of these variations in STA because these variations will effect the arrival and the required times if the signals in the timing paths. We apply OCV in STA with the help of Derates (scaling of the launch paths and capture paths depending on the check-setup or hold-).

AOCV: Advanced OCV=> This is also called location aware OCV In this we apply derating values on the cells/nets based on the logic depth from the common fanout point of the clock, ie: the point from which the launch and the capture clock bifurcate. This type of OCV needs AOCV tables in the timing libraries.
This OCV is more accurate and we can avoid adding unnecessary pessimism which gets added using OCV

thanks,
Shobhit
 

cyrax747

Full Member level 3
Joined
Nov 8, 2012
Messages
169
Helped
13
Reputation
26
Reaction score
11
Trophy points
1,298
Location
Bangalore
Activity points
2,485
Hi

From where does this derating values comes from ?? How much derate should i specify ?? On what factors does it depends upon ? How do we get this value ??
 

imsaurabh

Junior Member level 1
Joined
Feb 12, 2007
Messages
17
Helped
3
Reputation
6
Reaction score
3
Trophy points
1,283
Activity points
1,395
Hi,

OCV value usually comes from CHIP vendor after doing multiple simulations, legacy design data and scaling factor. (TSMC, GF).

Generally derate values vary from 5 -10% depending upon your chip, design, application and technology.
f you are top level designer, you should know your Temp, voltage and other parameters at the same time process variation from foundry and with simulation you can get a graph for best case and worst case values for device (bell curve.)

You have to use it depending upon accuracy you need.

Hope it helped.

Saurabh
 
Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top