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day_0_10-14-2015 [2015/10/14 06:43]
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day_0_10-14-2015 [2015/10/14 07:05] (current)
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 There is some background work that needs to be done before diving in and designing integrated circuits. There is some background work that needs to be done before diving in and designing integrated circuits.
  
-I probably won’t be doing any layout or fabrication on this blog since the entire process is quite expensive, even using services like MOSIS. ​ That said, there is still a need for circuit simulation software ​ and models for a handful of devices.+First, ones has to pick a process to design in. I probably won’t be doing very much layout or fabrication on this blog since it can be quite expensive, even using multi-project ​services like [[https://​www.mosis.com/​|MOSIS]].  That said, there is still a real need for circuit simulation software and models for a handful of devices.
  
-Models for AMI’s ​0.5um CMOS process ​is available ​ ​on ​bakers website.   The SPICE model file only includes NMOS and PMOS devices. Of course models are needed for diodes, BJTs, and resistors, but this is a good start.+ON Semiconductors C5 process (0.5um CMOS)is a great choice. ​ There are models available ​on the web [[http://​cmosedu.com/​jbaker/​courses/​ece5410/​s10/​C5_models.txt|Here]].   The SPICE model file only includes NMOS and PMOS devices. Of course models are needed for diodes, BJTs, and resistors, but this is a good start.  Also this is one of the few processes where a physical design kit(PDK) and open CAD software such as [[http://​www.staticfreesoft.com/​|Electric]] are available for free.  Typically, the PDK includes all of the specific information that one would need to design in a particular process. This includes: Design Rule Checking (DRC), LVS (Layout vs. Schematic), PCELLS (parameterized ​ drawings of each device in the process), and models for simulation. ​ Foundries usually only supply PDKs for a handful of CAD tools like the ones from Cadence, Mentor Graphics, and Synopsys.
  
- +For circuit simulation software, ​ there a number of free circuit simulators. ​ I’m going to be using Ngspice which is an open-source simulator based on an updated version of Berkley’s original ​ SPICE simulator. ​ There is no official GUI for this simulator, ​but it is actually quite easy to write net lists by hand. In addition, there are a number of free schematic capture programs ​to generate netlists graphically.  I'going to use [[http://​opencircuitdesign.com/​xcircuit/​|Xcircuit]] because it not only creates netlists, but also makes publication quality ​schematics.  ​Xcircuit has a clunky gui and crashes more frequently than I'd like, but overall the good outweighs the bad.
-The first thing to do is decide on what software to use. Typically companies use very expensive CAD tools for layout, circuit simulation, ​ and verification of integrated circuits. In addition to the CAD tools, one needs access to the PDK (Physical Design Kit) for the particular integrated circuit process that you want to design on. The PDK includes all of the specific information that you need to design in a particular process. This includes: Design Rule Checking (DRC), LVS (Layout vs. Schematic), PCELLS (parameterized ​ drawings of each device in the process), and models for simulation. +
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-For circuit simulation software, ​ there a number of free circuit simulators. ​ I’m going to be using Ngspice which is an open-source simulator based on an updated version of Berkley’s original ​ SPICE simulator. ​ There is no official GUI for this simulator, ​so the easiest way to use it is to write the netlist ​ files by hand. This is exactly what I’ve decided ​to do.  Inot sure what to use to makes schematics, for now, maybe just paper, pencil and my cell-phone camera.  ​LTSpice is another great free (but not open-source) circuit simulator that I may utilize from time to time.+
  
 Onward! Onward!
day_0_10-14-2015.txt · Last modified: 2015/10/14 07:05 by admin