So I am trying to design an OTA to meet the following specs:
View attachment 116641
Plus the following constraints:
The
maximum allowed transistor width is
W=100um.
The
maximum allowed transistor length is
L=20um.
The
maximum allowed capacitance (if you use Miller compensation) is
Cc=2pF.
The
supplies are
Vss=0 & Vdd=1.8V.
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I decided to go with the typical 2 stage miller OTA:
View attachment 116642
and the best result I got was (while meeting the specs)
GBW = 20 MHZ.
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- Is the miller OTA suitable for this design problem?
- Is there any rule of thumb on choosing the transistor's W and L?
- What is the maximum GBW that I can achieve while meeting the specs? (this will help decide if my design was okay, at least.)
NOTE: I checked few posts in the forum, and I saw a lot of designers suggest using the RFC OTA. I checked it and its design seems to be 10 times harder than the Miller OTA (I am still new to the analog design :grin