ADC Model, Getting Started
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Posted by auk_ie on March 15, 2005, 1:45 pm
Please log in for more thread options Hi all I'm trying to get back into electronics after a few years of neglect, My design revolves around a hi speed adc operating at 1Ghz from Maxim. So now I want to connect all the components together in PSpice. But the problem is the vendor doesn't provide a model for this ADC. So I guess I am forced to build a model of the ADC myself. I know this is a next to impossible task in spice. But all I want is to model an ADC at a behavioural level. I would like as many real worlds affects in the model as possible, but I hear thats a hard thing to do, so I would be happy with just a functional model of the ADC so I can proove my circuit in concept. What would be good is to have a model that accounts for the sample and hold, the conversion and the demultiplexed PECL outputs. I don't know where to start with this. I have looked at VHDL-AMS which looks like that it can do the job. But I can't find a simulator in which I can use my spice parts of the circuit and conect it up to the AMS based ADC model. PSpice is great because you can simulate spice models as well as vhdl/verilog parts. But not VHDL-AMS. I also looked at Matlab and Simulink. I think its possible to model such an ADC with these tools and then import the model back into pspice. But I have no resources on how to do this. I'm sure people have modelled an ADC in there designs before. Can anybody point me in the right direction? Tools to use? Workarounds etc.? | |||||||||||||||||||
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Posted by Kevin Aylward on March 16, 2005, 11:06 am
Please log in for more thread options auk_ie wrote: Oh dear... > But
> the problem is the vendor doesn't provide a model for this ADC. So I > guess I am forced to build a model of the ADC myself. I know this is a > next to impossible task in spice. Pretty easy if one knows what one is doing:-) > But all I want is to model an ADC at
> a behavioural level. I would like as many real worlds affects in the > model as possible, but I hear thats a hard thing to do, so I would be > happy with just a functional model of the ADC so I can proove my > circuit in concept. What would be good is to have a model that > accounts for the sample and hold, the conversion and the demultiplexed > PECL outputs. > > I don't know where to start with this. I have looked at VHDL-AMS which > looks like that it can do the job. But I can't find a simulator in > which I can use my spice parts of the circuit and conect it up to the > AMS based ADC model. PSpice is great because you can simulate spice > models as well as vhdl/verilog parts. But not VHDL-AMS. > > I also looked at Matlab and Simulink. I think its possible to model > such an ADC with these tools and then import the model back into > pspice. But I have no resources on how to do this. > > I'm sure people have modelled an ADC in there designs before. Can > anybody point me in the right direction? Tools to use? Workarounds > etc.? Yes. I shall of course, force you to download my SuperSpice (http://www.anasoft.co.uk ) demo in order for you to get your model. It is an interesting post, as when I first looked at this issue myself, I could not find any generic spice models that did this rather basic function. It was a case of reinventing the wheel. The AD model I finally came up with is an instantaneous successive approximation using simple spice primatives. Open the example 16Bit-AD-DA.sss, and press the blue "R" button to run it. Move the test point to see the digital logic levels. If you click on the adc and dac symbols the model text will show up in the top left docked window. The models will run in any spice. The model themselves are in AnalogDigitalLogic.lib. There are 4, 8 an 16 bit versions of both ad and da. Have a go at decoding what the block diagram of the technique is. Kevin Aylward salesEXTRACT@anasoft.co.uk http://www.anasoft.co.uk SuperSpice, a very affordable Mixed-Mode Windows Simulator with Schematic Capture, Waveform Display, FFT's and Filter Design. | |||||||||||||||||||
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Posted by Charles Edmondson on March 16, 2005, 2:10 pm
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auk_ie wrote: > Hi all
Look in the dataconv library, and you should see several ADCs listed
> > I'm trying to get back into electronics after a few years of neglect, > My design revolves around a hi speed adc operating at 1Ghz from Maxim. > > So now I want to connect all the components together in PSpice. But > the problem is the vendor doesn't provide a model for this ADC. So I > guess I am forced to build a model of the ADC myself. I know this is a > next to impossible task in spice. But all I want is to model an ADC at > a behavioural level. I would like as many real worlds affects in the > model as possible, but I hear thats a hard thing to do, so I would be > happy with just a functional model of the ADC so I can proove my > circuit in concept. What would be good is to have a model that > accounts for the sample and hold, the conversion and the demultiplexed > PECL outputs. > > I don't know where to start with this. I have looked at VHDL-AMS which > looks like that it can do the job. But I can't find a simulator in > which I can use my spice parts of the circuit and conect it up to the > AMS based ADC model. PSpice is great because you can simulate spice > models as well as vhdl/verilog parts. But not VHDL-AMS. > > I also looked at Matlab and Simulink. I think its possible to model > such an ADC with these tools and then import the model back into > pspice. But I have no resources on how to do this. > > I'm sure people have modelled an ADC in there designs before. Can > anybody point me in the right direction? Tools to use? Workarounds > etc.? there. Place one and descend into it, and you will see what is necessary to model an ADC in PSpice... -- Charlie -- Edmondson Engineering Unique Solutions to Unusual Problems | |||||||||||||||||||
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>
> I'm trying to get back into electronics after a few years of neglect,
> My design revolves around a hi speed adc operating at 1Ghz from Maxim.
>
> So now I want to connect all the components together in PSpice.