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#analog-design
Title
# analog-design
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Matt Venn

09/03/2021, 4:05 PM
what's going to be fastest driving a load? 1, 2 or 3 stages of inverters. I would have previously said 1, but in this case it's 3
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Matthew Guthaus

09/03/2021, 4:34 PM
If you want the quickest estimate, try to have the ratio of sizes be always ~3-4.
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Boris Murmann

09/03/2021, 5:11 PM
These slides may be helpful.
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Luis Henrique Rodovalho

09/03/2021, 10:15 PM
What is the load? Another minimum size inverter? The three stage inverter is better for driving a larger load. I think that the best way to characterize inverter delay is with ring oscillators.
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20Mhz

09/03/2021, 10:24 PM
Btw, I did FO4 delay here: https://github.com/20Mhz/spice_decks/tree/sky130/calib as hinted above and mentioned in the slides, best case is having geometric mean as fanout. cheers
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Tom

09/04/2021, 8:01 AM
"Logical effort" is a technique I remember learning about for performing back-of-the-envelope calculations on exactly this. There's a Wikipedia article on it here https://en.m.wikipedia.org/wiki/Logical_effort