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Feb 24th, 2021, 10:07am
1  Design Languages / Verilog-AMS / Re: Writing to a file for DNL calculations of an ADC
 on: Feb 19th, 2021, 5:29am 
Started by K22 | Post by Horror Vacui
It would have been nice to share to solution for others...

2  Design / Analog Design / Re: DNL/INL simulation of a delta sigma ADC
 on: Feb 17th, 2021, 7:53pm 
Started by saralandry | Post by asu2011
no dnl/inl simulation for sd adc

3  Other CAD Tools / Entry Tools / Revolution EDA or RevEDA
 on: Feb 15th, 2021, 2:43am 
Started by Murat H. Eskiyerli | Post by Murat H. Eskiyerli
We decided to create a useful and productive tool-flow from available free/open-source tools. The first result of this work is now called RevEDA and includes Glade Schematic/Layout Editors including Gemini DRC/LVS and Xyce circuit simulator as well as RevEDA simulation GUI. A short video showcasing its status was uploaded to Youtube a week ago.

I thought it might be interesting for some members. If it is,  please contact me and I will try to answer your questions.

Murat Eskiyerli

4  Other CAD Tools / Physical Verification, Extraction and Analysis / Re: PEX R+C Extraction: How to set minimum cap and minimum R
 on: Feb 12th, 2021, 8:38pm 
Started by S.ARYA | Post by Maks
Long extraction time is a typical problem with parasitic extraction.

If your design is large in size, well, it's extraction will take time.

I would suggest to make sure there are no issues with the extraction setup / flow. Are you the first to use this flow, or are there other designers in your organization, who use it? What about their extraction time - is it too long, or OK?
Was extraction setup prepared by a knowledgeable person?

There are a number of settings or tricks that you can use to speed up the extraction.
For example, you can set Cmin and Rmin values - so that any capacitance or resistance below that will be ignored.
But beware of possible accuracy loss.
Also, you can extract in RC-decoupled mode, where all coupling capacitances are redirected to ground.

Do you need to extract power nets? These are huge things, and may take the major portion of the extraction time. Often, analog designers do not extract power nets, i.e. power nets are treated as ideal nodes.

There are a bunch of other things that you can or should check, or tricks that you can use, to speed up the extraction.

Of course, if your vendor (Mentor in this case) provides a good support, you can ask them to help.

5  Design / Analog Design / A GFSK demodulator for low-IF Bluetooth receiver
 on: Feb 11th, 2021, 1:49am 
Started by blue111 | Post by blue111
For A GFSK demodulator for low-IF Bluetooth receiver , how does the shape-keeping circuit in figure 4(c) works ?

Besides, why need the NOR gate before the input to the shape-keeping circuit ?

Why if R3 is changed to 50 ohm, then the whole circuit cannot simulate at all ?  

6  General / Tech Talk / Estimating and planning
 on: Feb 5th, 2021, 4:20pm 
Started by Peruzzi | Post by Peruzzi
How do you come up with your first rough estimate for how long it takes to design a circuit, its area, and current consumption?
In particular, say you had to add a high pass filter (to boost high frequencies) to a SERDES receiver, that wasn’t already there.  Just a hand-waving approximation of how many weeks it would take to design, verify, layout, post layout verify, and get first samples from the foundry. How much current it would draw, and how big it would be.  Say, for 45 nm.
Nobody’s going to hire you or me to do this.  Just an approximation.
You’re not committing to any accuracy here.  I appreciate it.
Bob P.

7  Design / Mixed-Signal Design / Delay Line
 on: Feb 4th, 2021, 10:46pm 
Started by Cascody | Post by Cascody
I have to delay a digital pulse by 30ns with an accuracy of ~1ps. Can this be achieved using the inverter chain delay line? If not, please suggest a topology. I couldn't find much literature on this.

I am using TSMC 65nm process.

8  Simulators / Circuit Simulators / Re: Root locus and Nyquist plots in cadence virtuoso ADE
 on: Feb 1st, 2021, 7:53pm 
Started by iVenky | Post by iVenky
I see. Thanks! I wish there was a way to find the location of poles and zeros approximately with stb analysis if I input an estimate of number of poles and zeros in the system.

9  Simulators / Circuit Simulators / Re: Root locus and Nyquist plots in cadence virtuoso ADE
 on: Feb 1st, 2021, 1:08am 
Started by iVenky | Post by Frank Wiedmann
I don't think so. Spectre also has a pz analysis, but I have never used it.

10  Simulators / Circuit Simulators / Re: Root locus and Nyquist plots in cadence virtuoso ADE
 on: Jan 29th, 2021, 3:09pm 
Started by iVenky | Post by iVenky
Is it fundamentally possible to find poles and zeros in stb analysis?

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