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Design Languages >> Verilog-AMS >> How to access current of a wreal port in pure digital environment?
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Message started by pipeline on Dec 1^st, 2010, 7:04am

Title: How to access current of a wreal port in pure digital environment?
Post by pipeline on Dec 1^st, 2010, 7:04am

I want to write some behavior model using wreal for digital verification, but encounter an issue accessing current for a voltage wreal port. The detailed description is attached. Without using Verilog-A electrical discipline, how can I handle such case? Need your help, thanks.

Title: Re: How to access current of a wreal port in pure digital environment?
Post by jerome_ams on Dec 2^nd, 2010, 1:55am

Hi,

The wreal approach is a nice way to handle real signals, which then can be used to describe analog-like quantities, in a pure event driven simulation (digital simulator). This real signal could represent eitherway a voltage, or a current, but there is no physical meaning here, no electrical discipline... It is just a real signal, which the designer uses to represent something...
The Verilog-A(MS) has been developped to cover this analog physical representation, defining disciplines to formulate the voltage/current duality.
So, I would say take benefit of the VerilogAMS to achieve what u want here.
U can connect wreal to electrical, and get good results if u set properly the ConnectModules in between.

Cheers,
Jerome

Title: Re: How to access current of a wreal port in pure digital environment?
Post by jerome_ams on Dec 2^nd, 2010, 1:59am

or u can process the wreal input (U) of your load, to compute a signal named for instance I (I=U/R) which will be triggered by U... This internal I signal is a real, which "represents" a current... But it won t be probed as a current, but as a digital real signal

Title: Re: How to access current of a wreal port in pure digital environment?
Post by jbdavid on Dec 2^nd, 2010, 4:51pm

wreal is one value one way all the time, at least as currently defined by the most recent version of the AMS LRM.
Even if you are using electrical discipline, if its a Voltage driven from outside, you cannot sense, the current, you have to DRIVE the current, as appropriate to the voltage coming in. the node driving the voltage will sense the TOTAL current coming from all loads.
In the electrical world you can drive either voltage or current, but not both. and you can sense either, but you have to drive the other.
or your network is indeterminate.