Sameer, The if-use form and the single simultaneous statement are strictly equivalent. The former explicitly defines which aspect of the source must be considered when performing a particular analysis. The latter combines both aspects in a single statement. In that case, the ac_spec term is ignored when performing DC or time-domain simulation, while the DC term is ignored when performing small-signal AC simulation. This can be done since ac_spec is a special kind of quantity. Best regards, Alain Vachoux Sameer Kher wrote: > Hi All, > > I was seeking a clarification regarding the behavior of a VHDL-AMS > simultaneous statement during frequency analysis. Any help is greatly > appreciated. > > Consider the following source model - this model is similar to the one > in the "The System Designer's Guide to VHDL-AMS" by Peter Ashenden (pp 407). > > LIBRARY IEEE; > USE IEEE.MATH_REAL.MATH_2_PI; > USE IEEE.ELECTRICAL_SYSTEMS.ALL; > ENTITY E IS > PORT (QUANTITY DC : IN VOLTAGE := 1.0; > QUANTITY AC_MAG : IN VOLTAGE := 1.0; > QUANTITY AC_PHASE : IN ANGLE := 0.0; > TERMINAL p,m: ELECTRICAL); > END ENTITY E; > ARCHITECTURE behav OF E IS > QUANTITY v ACROSS i THROUGH p TO m; > QUANTITY ac_spec : real SPECTRUM AC_MAG, MATH_2_PI*AC_PHASE/360.0; > BEGIN > IF (domain = quiescent_domain) OR (domain = time_domain) USE > v == DC; > ELSE > v == ac_spec; > END USE; > END ARCHITECTURE behav; > > My question is - Why is the if-use required at all? Wouldn't the same > effect be achieved by using the following simultaneous statement - > > v == DC + ac_spec; > > i.e. Does the quantity DC have any contribution in the frequency domain? > > Thanks, > Sameer > > -- > This message has been scanned for viruses and > dangerous content by *MailScanner* <http://www.mailscanner.info/>, and is > believed to be clean. -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.Received on Thu Sep 13 23:37:23 2007
This archive was generated by hypermail 2.1.8 : Thu Sep 13 2007 - 23:37:55 PDT