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Hi Denis,
Thanks for your response. It is very helpful.
Even before I can measure offset of my folded cascode OTA, I am facing error while measuring the open loop gain of the OTA.
I do the following in my MC simulations:
1) Provide input Vcm to the OTA and leave OTA in the open loop.
2) Set...
Hi Dennis,
Thanks a lot !!! This is very useful information that you have shared with me. Many thanks for it. Following your instruction i have created a quick schematic of test bench. Though might be useful to other community fellas. Can you please cross verify whether its correct or not...
Hi Erikl,
Actual I found the solution to measure distortion a day later.
I came across same question on the forum so thought of sharing it with other community members.
Anyways thanks for point that link to this thread. It might help other people.
Regards
Nandish
Hi Denis,
I have done the offset calculation of my folded cascode OTA.
In my test bench OTA is configured as unity gain buffer. Then using wavescan I measure the difference between input and output during monte-carlo simulation with Mis-Match & process variation. The resultant file is imported...
Another solution is to bootstrap your switch. with TG switch or with NMOS/PMOS channel charge depends on the input voltage. With the bootstrapping you can atleast make the it independent of input voltage and then make it appear as common mode signal to the succeeding stage OTA so that it gets...
you need to do DFT and look at the difference between fundamental and the nearest bin. Note that the key in getting proper distortion number is to perform dft properly.
you need to set Fin = (n/N) fs
where n is a prime number and N is number of points of DFT e.g. 1024 (2^b).
This relation is...
Hi Friends,
Can any one point me a method to measure the distortion of a boot strapped switch?
I am using SPECTRE simulator. Is there any prescribed method for measuring the distortion caused by switch?
Please kindly oblige with your suggestions.
Regards
Nandish
Re: Basic Question
It's simple. Think of it in this way. Say you have a folded cascode with PMOS input pair. Let the bias current for the input pair be Ibias. Then the current from input pair has to be sinked by NMOS current source at the folding node. Hence the NMOS tail current source has...
I am also facing similar problem. Mis-match is screwing my open loop gain. For e.g. i ran MC for 30 iterations (suggested by UMC MC datasheet) and my open loop gain which was designed for around 7K drops to few 1K. Only one or two iterations hits my open-loop gain.
I will highly appreciate any...
If you are simulating a differential OTA only mismatch will cause offset in your circuit. For mis-match you can refer to your model file for the parameter that MC simulation will vary with 3 Sigma deviation and gaussian as distribution.
I think most of the foundry in their MC characterisation...
hi friend,
many thanks for taking time out to reply my query ...
actually i have resolved my problem ....
issue was spectre was not getting lincense from server ... so i added my IP and server IP address in /etc/hosts
now it works perfectly fine ...
thanks again for your response neil
Hi friends,
I have recently copied Cadence from server in our college to my local machine. Everything works fine like starting ICFB, schematic editor and even ADE but when I run simulation, spectre stops at one particular .so file. Output is as like below:
Command line...
hi,
use .ic statement to initialize the node and no need for startup circuit ....
you can simulate start-up circuit separately too.... advantage of using .ic is that it will allow you to do estimation of total noise in the Bandgap ref ckt. else with start-up it may pop error as start-up will...
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