On Fri, Nov 7, 2008 at 5:44 PM, Kai-Martin Knaak <[EMAIL PROTECTED]> wrote: > On Fri, 07 Nov 2008 12:37:30 +0100, Stephan Boettcher wrote: > >> Why do you want power symbols? > > Analog circuits require dedicated capacitors at the power pins.
I agree. In analog IC design (this is my field) things went both a bit further and in slightly different direction. People are partitioning schematics exactly as they would partition the layout (using a design hierarchy). This implies that slotted symbols may not be used, even in situations where it would make sense (e.g. an integrated multichannel cell). It is not uncommon to model supply or critical signal tracks explicitly to handle signal integrity issues, supply/ground noise etc. The main difference from the component-level world is that in the IC design tools are strongly focused on simulation, both of the schematics and the layout. Typical designs are also more complex so it is better not to rely on the layout designer intuition (even if it is the same person as the circuit designer). Implicit pins are commonly forbidden. I've even seen guidelines prohibiting implicit net connections (by named nets) or large flat schematics (say, larger than an A3 size page). These problems are slowly drifting to the component-level world. Slotted devices almost don't exist (except maybe for 74XXX type devices) and even if they do, it's is still better to instantiate them explicitly (like using e a single symbol for a 4x opamp). Simulation becomes a part of the design flow, at least for parts of the system, as well as does the extraction of the PCB parasitics. -r. _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
