Basic question from a novice

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analog_ambi

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Hi,
I want to design a low power OTA operating in subthreshold region for my college project. I dont have any practical exposure. I have ncsu pdk. How shall i start my design?

I have heard that in industry people do initial simulations with current mirror and find cgs, gm to find ft. I want to approach like that. using ft how shall i proceed to size my transistor to complete the design. Please help!
 

If i am given a technology file what are the immediate specs of the op amp which i can derive through some basic simulation using current mirror?
 

The current mirror concept makes it possible for the op amp to amplify the difference between two arbitrary inputs. This makes the op amp more versatile than a single transistor.

The current mirror also allows the op amp to always output some current flow (power). It is never hi impedance. A single transistor isn't quite as versatile.

Here's a website showing a circuit for an op amp made from discrete components. The fellow who runs it is exceptionally good at explaining how transistor circuits function.

4QD-TEC: discrete op-amps

Here's another useful website. With current mirror, differential amplifier, simple op amp. With Spice code samples. These are in the bottom half of the webpage (which presents numerous other circuits).
 

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