Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
Dear Audioguru
what to you does not look like a "normal" schematic is the de-facto standard for IC design engineers, it is called Cadence Composer and you don't want to know how much a year of license maintenance costs, much less what the initial license cost is...
I don't think the...
Hi Vlad
I am not familiar with the exact circuit you are designing, still in general the input linear range depends mostly on the inversion coefficient of the input pair: it is minimum in weak inversion and grows significantly as you move into stronger inversion.
I am guessing your bias...
There are various options to achieve that depending on how the rule file is set up:
- you might simply have to define or redefine an internal calibre variable
- you might have to add SVRF commands in the inlude section
- you might have to change the rule file
In any case you'll have to look...
Hi abcyin
This can happen under various circumstances most typically when there is a jog on the gate (45deg turns) used in commercial std cells to increase density.
The simplest option is to ignore it or better verify that these little violations are not masking important ones by temporarily...
Hi yannik33
To have any intrinsic gain your input device has to be in saturation, similarly a current source has to be in saturation to have high output impedance; the output dynamic range is then given by the voltage domain that can keep both the input device and the current source in...
Hi yannik33
Assuming your bias current source has sufficiently high impedance, the intrinsic gain gm/gds of your input device determines the common source gain. Intrinsic gain grows as you lower your inversion level, which is prop to bias current. Bias current buys you bandwidth not gain. So no...
Most moderm simulator allow placing a 0 V source within the loop and run a specific analysis to simulate the loop gain. The method used is usually Tian's. What simulator are you using ?
Hi Diarmuid,
Sorry did not get to review your doc in full, it will be a busy week for me...
Here a few tips:
If the sigma block in your diagram has a plus on the feedback input then the sign in the loop gain (at the denominator of the closed loop gain ) is wrong. Just change the sigma symbol so...
Hi anhnha,
I will not subscribe to all the advice you have received here so far; I have had my fair share of pain with similar bandgap stability issues so I had to do a fair share of digging:
- 'cutting' all loops with iprobe (or simply a 0V source) is exactly what Tian method requires (which...
Hi heein
Are you sure you are loading the PEX ruledeck and not che technology description file (occasionally called rules)? Very often the pex rule deck is the same as the LVS rules with an additional internal variable set to -among other things- include the stack description file (usually only...
Hi LvW
Thanks for the link, I skimmed through it but I cannot tell under what assumption this works. I'll ask if you've had some experience with it.
I am always interested in new stability criteria... Let's call it an hobby. Feel free to post here or privately if you feel it is off topic.
As...
Hi LvW
Tian's method does indeed include a double injection (current+voltage) as the older Middlebrook method (1976) [but it is more complete than Middlebrook's old method as it consider bilateral blocks to accounts for feedforward, in response Middlebrook came up with a new method accounting...
Thermal noise for hand calculation is most simply expressed as a drain current noise
Idn=4 k T Γ g_ms
where g_ms is the source transconductance and Γ a factor smoothly varying from 1/2 in weak inversion to 2/3 in strong inversion. It is valid for all regions of operation.
As of flicker that's a...
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
