I m going to be working on some RF related co

Question

< U017T7ECQAX> I m going to be working on some RF related components gilbert cell VCO PLL etc Looking for someone with some asic design background to help me out I ve got board level radio design experience but no asic

yrrapt · Answer

What in particular are you looking for help with

Trevor Clarke · Answer

Realizing the circuits with available primitives for example which type of FET primitive to choose placement in the cell etc

Trevor Clarke · Answer

but I m open to any help circuit design parameter specing etc

yrrapt · Answer

I see I would probably recommend just starting a simple 5 transistor operational amplifier Go from to specs to layout There are lots of tutorials in written and video form talking through the various steps Once you ve got an idea of the flow you can start branching out to the circuits you re thinking of

yrrapt · Answer

I m sure people will be happy to answer specific questions as they come up

Sutton Hathorn · Answer

I second yrappt the classic first tutorial is building an opamp If you re rusty on sizing etc I d start by reviewing gm id design techniques I think <http web02 gonzaga edu faculty talarico EE406 documents gmid pdf> gives a decent approach

Trevor Clarke · Answer

thanks for the references I ll probably start with the Gilbert cell as it s in my list and is as simple and straightforward as a basic opamp 6 FETs and some biasing a couple of balums if you re feeling feisty

Trevor Clarke · Answer

As far as workflow I assume my first task would be simulation with spice I believe the models aren t available yet and schematic refinement Then physical layout of the cell non parameterized so I assume I wouldn t be using something like BAG Is magic the tool for that Does it import a schematic I ll need to go through the magic docs eventually just planning the particular spice and schematic capture tool to use

tnt · Answer

AFAIK no magic doesn t import a schematic

tnt · Answer

but after layout you go through extraction and LVS checking that compares the extracted netlist of your layout with your reference schematics to check they indeed are the same thing

tnt · Answer

My bad it can actually import a netlist Not a schematic so I think you still need to have drawn your cells primitives but the interconnect between them can be imported for interactive routing I guess

Trevor Clarke · Answer

so it doesn t matter much which schematic tool I use as long as it generates a netlist

tnt · Answer

It s actually something being evaluated right now which schematic tool is going to be recommended But yeah in theory you could pretty much use any ideally it needs to support attributes on symbols to specify which type of FET channel width length

Trevor Clarke · Answer

Hmm I ll have to see if kicad can generate the attributes if not I m guessing gEDA has something that will gschem I think it is

yrrapt · Answer

Most IC layout tools don t have interactive routing like you re used to from PCB tools You draw the shapes wires and run LVS and hope they match I expect magic will be the same

tnt · Answer

Kicad is one of the tool being considered although the nightly build future 6 0 since the schematic format changes Alternative would be xschem which is more natively oriented for that kind of use

Trevor Clarke · Answer

Thanks I ve got a machine at home that generally tracks master for kicad so I can give that a shot

Sutton Hathorn · Answer

< yrrapt> virtuoso xl and above have many features that mimic interactive routing when using the path tool

Sutton Hathorn · Answer

obviously virtuoso is not an option for a hobby user so for this PDK it will certainly feel different than PCB design

yrrapt · Answer

I use virtuoso layout L professionally unfortunately license costs means XL isn t an option I ve been told its cheaper to to pay the extra hours of work than pay the extra for the XL licenses A crazy situation I m really hoping some tool improvements come from this open sourcing of IC design

Josh Marks · Answer

< Trevor Clarke> happy to help in anyway