Difference between OCEAN and MDL

Dear agrawal,

gagrawal said:

was wondering what is the advantage of using MDL over OCEAN ? In my limited knowledge, OCEAN is a super-set and can be used to perform a wider variety of tasks as compared to MDL. Am I missing the specific reason why MDL is used / even exists ?

ocean can be used to access simulation results for any simulator supported by the Analog Design Environment while spectre MDL is spectre specific. Both are text file driven. Spectre MDL does not, in my opinion, have the "overhead" of ocean and hence appears to run faster than ocean for a similar measurement. However, ocean supports SKILL and its language and can be quite powerful for post-processing data (once gain, my opinion!).

Other experts who monitor this forum likely can provide a more extensive comparison of ocean with spectre MDL, but these comments reflect my understanding (hopefully accurate!).

In case you have not seen it, there are a series of short videos ("training bytes") on the Cadence On-line support site starting with one detailing a few major differences between spectre MDL and ocean. This video may be accessed at URL:

support.cadence.com/.../ArticleAttachmentPortal

It is followed by a number of additional short videos, the first of which provides an example of the use of an MDL file to both run and post-process a set of simple spectre AC/DC simulations.

There is also a spectre MDL Rapid Adoption Kit at the On-line support site at URL:

support.cadence.com/.../ArticleAttachmentPortal

I hope this is somewhat helpful agrawal!

Shawn

Dear agrawal,

gagrawal said:

was wondering what is the advantage of using MDL over OCEAN ? In my limited knowledge, OCEAN is a super-set and can be used to perform a wider variety of tasks as compared to MDL. Am I missing the specific reason why MDL is used / even exists ?

ocean can be used to access simulation results for any simulator supported by the Analog Design Environment while spectre MDL is spectre specific. Both are text file driven. Spectre MDL does not, in my opinion, have the "overhead" of ocean and hence appears to run faster than ocean for a similar measurement. However, ocean supports SKILL and its language and can be quite powerful for post-processing data (once gain, my opinion!).

Other experts who monitor this forum likely can provide a more extensive comparison of ocean with spectre MDL, but these comments reflect my understanding (hopefully accurate!).

In case you have not seen it, there are a series of short videos ("training bytes") on the Cadence On-line support site starting with one detailing a few major differences between spectre MDL and ocean. This video may be accessed at URL:

support.cadence.com/.../ArticleAttachmentPortal

It is followed by a number of additional short videos, the first of which provides an example of the use of an MDL file to both run and post-process a set of simple spectre AC/DC simulations.

There is also a spectre MDL Rapid Adoption Kit at the On-line support site at URL:

support.cadence.com/.../ArticleAttachmentPortal

I hope this is somewhat helpful agrawal!

Shawn

In addition to the useful answers and pointers from Shawn, a few other points:

• MDL is run within the simulator - as such, this means that it's well-suited for a command-line Spectre user as the approach is quite Spectre-like and doesn't need you to use a larger executable such as Virtuoso to control/post-process your results
• MDL can also be used to make measurements during simulation, and auto-stop when they've been met - so for characterisation tasks (such as setup/hold) this can be more efficient
• MDL also gives access to some simple search and multi-variable optimisation within the simulator - so whilst not as powerful as the optimisers in ADE, it's much faster
• MDL is however quite limited in the functions available, and doesn't really handle things like RF analyses.
• OCEAN is more extendable, but is very much a means of controlling whole simulations and analysing the results from whole simulations. Because OCEAN is just a set of SKILL functions, the language has not been designed specifically with simulation in mind and so it can appear a little clunky compared with MDL which was designed specifically for the purposes of making measurements in simulation - although SKILL has the upside that comes from being a pretty broad programming language.
• OCEAN tends to be more natural for somebody used to using ADE as it fits alongside ADE (it's using the ADE infrastructure underneath).
• So there are pluses and minuses of both - which is why both exist. Historically, OCEAN has been around for longer, and when MDL was first created there was a thought that it would replace OCEAN for calculations, doing measurement-centric simulation and so on - but in practice the need for legacy support and also the fact that MDL was specific to Spectre meant that didn't quite pan out (some may remember in the past that the waveform tool at the time, wavescan, initially was for MDL, then extended to have two language modes, and finally dropped the MDL mode.

Andrew

Dear Andrew,

THANK you for adding your insight on the differences between the ocean and MDL - and a bit of the history! This was quite interesting - and yes - I do remember wavescan. I am sure your added information will be useful for gagrawal!

Shawn