Where will you place macros in your core and why?

macro placement

Hi All,

1) Where will you place macros in your core and why?

mean to ask, at the centre or at the core boundary.

Re: macro placement

You will be placing them at the boundary.In order to minimize routing resources.Also, your PnR tool will achieve a better global soln for placement if you place the macros at the boundary.

But you can place at the centre if your design requirements force you to place.

Re: macro placement

thanks teja,

please tell me one more thing....................

are the macros more power hungary compared to rest of the design?

if this is true then this may be one of the reason to place them at the boundary so IR drop will be less for these macros from power/ground ring to the macros rings/pins.

but i have doubt whether macros are more power hungary or not?

macro placement

hi jitendrda,
Can you elaborate on what you mean by macros,, are you saying its a macro logic box or any memory instantiations

Re: macro placement

macro means it can be either soft or hard macro

e.g RAM, PLL, ADC, DAC, etc...............

Re: macro placement

HI,

for the macro placement first do the flyline analysis, that is analyze the connections between modelpins and macro and macro to the combo logic, and macro to macro. this will give you the idea about the placement of macro with optimal routing resources.

Thanks..
HAK..

Re: macro placement

Dear Kotak,

Are macros more power hungry compared to rest of the design?

thanx
jit

macro placement

depends on the kind of macr if its memory element or ip or other kinds



BR

SING

Re: macro placement

Hi jitendravlsi,

There are several advantages keeping Macros at the boundary.

1) Yes, Macros are power hungry to some extent, depends on the logic inside. But yes compared to std cells they are.
There are custom Analog/Digital macros needs to connect with wide metals also.

One reason we keep at boundary is,
In Ring style power routing we provide power routing along the boundary of core area and hence distance from here to Macro reduced and hence resistance reduced.

But in Mesh style power routing it does not matter where you keep, only make sure that the power port is close and width requirement of Macro taps are maintained.

2) coming to second advantage,
IO to core logic connection is very less compared to Macro to core logic. Hence throughing the macros to boundary facing their pins to Core makes std cells good accesibility.

depending on the above two we can have macro placement

enjoy