| Author |
Message |
bowling
Joined: 19 Oct 2005
Posts: 3
|
 Posted:
Thu Oct 20, 2005 2:39 am Post subject:
how to adjust parameters of low hierarchy |
|
|
Hi guys,
I am a new user of Cadence. Please don't ignore my question if you think it's too stupid. 
I created a schematic then a symbol of logic inverter with NMOS and PMOS. Then used it to create a schematic, say D flip-flop, with the inverter symbol. I'd like to change the number of fingers of PMOS/NMOS in the inverter I used in D flip-flop in order to increase the maximum speed which D flip-flop can operate at. I know I can achieve that by "hierarchy edit", but I don't wanna change the parameters of the inverter permanently. Because I also use it in some other schematics. How can I do that? cdf? skill? hierachy editor? or shall I make a copy of the inverter that dedicates to the particular schematic only? Is it possible to add low hierarchy parameters (i.e. number of fingers of PMOS/NMOS) to the properties of the high hierarchy schematic (i.e. D flip-flop in this case), so that I can adjust parameters conveniently in the D filop-flop schematic?
I highly appreciate your help!
|
|
| Back to top |
|
 |
Bernd Fischer
Guest
|
| Posted:
Thu Oct 20, 2005 12:10 pm Post subject:
Re: how to adjust parameters of low hierarchy |
|
|
e.g. use in the number of fingers filed
of the edit properties of your inverter pPar("nof")
this will pass the parameter 'nof' one hierarchy level up.
See
'Virtuoso Analog Design Environment User Guide'
'Design Variables and Simulation Files {[or Direct Simulation]'
'Passed Parameter Value of One Level Higher: pPar()'
Maybe this helps you.
Bernd
bowling wrote:
| Quote: | Hi guys,
I am a new user of Cadence. Please don't ignore my question if you
think it's too stupid. :wink:
I created a schematic then a symbol of logic inverter with NMOS and
PMOS. Then used it to create a schematic, say D flip-flop, with the
inverter symbol. I'd like to change the number of fingers of
PMOS/NMOS in the inverter I used in D flip-flop in order to increase
the maximum speed which D flip-flop can operate at. I know I can
achieve that by "hierarchy edit", but I don't wanna change the
parameters of the inverter permanently. Because I also use it in some
other schematics. How can I do that? cdf? skill? hierachy editor? or
shall I make a copy of the inverter that dedicates to the particular
schematic only? Is it possible to add low hierarchy parameters (i.e.
number of fingers of PMOS/NMOS) to the properties of the high
hierarchy schematic (i.e. D flip-flop in this case), so that I can
adjust parameters conveniently in the D filop-flop schematic?
I highly appreciate your help!
|
|
|
| Back to top |
|
|
Svenn Are Bjerkem
Guest
|
| Posted:
Thu Oct 20, 2005 12:10 pm Post subject:
Re: how to adjust parameters of low hierarchy |
|
|
In article <IPidnco31vJ5zcreRVn_vA@giganews.com>,
bowlingwangke@yahoo.co-dot-uk.no-spam.invalid says...
| Quote: | Hi guys,
I am a new user of Cadence. Please don't ignore my question if you
think it's too stupid. :wink:
I created a schematic then a symbol of logic inverter with NMOS and
PMOS. Then used it to create a schematic, say D flip-flop, with the
inverter symbol. I'd like to change the number of fingers of
PMOS/NMOS in the inverter I used in D flip-flop in order to increase
the maximum speed which D flip-flop can operate at. I know I can
achieve that by "hierarchy edit", but I don't wanna change the
parameters of the inverter permanently. Because I also use it in some
other schematics. How can I do that? cdf? skill? hierachy editor? or
shall I make a copy of the inverter that dedicates to the particular
schematic only? Is it possible to add low hierarchy parameters (i.e.
number of fingers of PMOS/NMOS) to the properties of the high
hierarchy schematic (i.e. D flip-flop in this case), so that I can
adjust parameters conveniently in the D filop-flop schematic?
|
investigate into using pPar() in your D-flip flop. Then you can change
properties of underlying modules on a "per instance" base.
On the transistor parameter you want to have parametrized place a pPar()
like: W=pPar("w"), then recreate your symbol to get the CDB right (or
edit CDF manually (if you already have a symbol copy it away and then
insert it again later))
Place these custom cells in your D-Flip flop and place a new pPar on
each property you want to propagate to the next level. If you want cells
with individual parameters, then you have to create unique pPar()
parameters for each cell. Then recreate your DFF symbol to update CDF.
Now you can place These DFF's with different walues for the transistor
parameters you have propagated bottom up.
This involves quite a lot of work, especially if you want to mimic
different "drive strengths" of your basic cell library at level two, but
at least you can get your task done. Maybe there is a much simpler way
which I haven't discovered.
--
Svenn
|
|
| Back to top |
|
|
bowling
Joined: 19 Oct 2005
Posts: 3
|
| Posted:
Fri Oct 21, 2005 4:59 am Post subject:
re:how to adjust parameters of low hierarchy |
|
|
| Tons of thanks to Bernd and Svenn!! Hope there are alternative ways of doing it coming up. |
|
| Back to top |
|
|
bowling
Joined: 19 Oct 2005
Posts: 3
|
| Posted:
Fri Oct 21, 2005 7:25 am Post subject:
re:how to adjust parameters of low hierarchy |
|
|
| where can i get the 'Virtuoso Analog Design Environment User Guide'? |
|
| Back to top |
|
|
Bernd Fischer
Guest
|
| Posted:
Fri Oct 21, 2005 12:10 pm Post subject:
Re: how to adjust parameters of low hierarchy |
|
|
/<dfII_inst_dir>/doc/anasimhelp/anasimhelp.pdf
or just type 'cdsdoc' in your terminal.
'cdsdoc' is the online help system, and it is essential!
Bernd
bowling wrote:
| Quote: | where can i get the 'Virtuoso Analog Design Environment User Guide'?
|
|
|
| Back to top |
|
|
|
|
|
|
FAQ
Memberlist
Register
Profile
Log in to check your private messages
Log in
