Describe Folded Cascode Operational Amplifier

Subject: CMOS VLSI Design

Topic: MOS Operational Amplifiers

Difficulty: Medium

cvd • 781  views

Folded Cascode opamps:

i) In order to reduce the drawbacks of Telescopic cascode opamp namely, limited output swing and difficulty in shorting the input and output, a folded cascade opamp can be used.

ii) In folded cascode, unlike telescope cascode, we use NMOS and PMOS to form a cascode.

enter image description here

iii) The folding idea explained above, can easily be applied to opamps as shown below:

enter image description here

$|A_v| \approx gm_1{[(gm_3+gmb_3)r_{o3}(r_{o1}||r_o5)] \,||\,[(gm_7+gm_7)r_{o2}*r_{09}]}$

enter image description here


  • Slightly higher swing, input and output can be shorted.


  • Gain trades off with $V_{in}$ swing.
Please log in to add an answer.

Next up

Read More Questions

If you are looking for answer to specific questions, you can search them here. We'll find the best answer for you.


Study Full Subject

If you are looking for good study material, you can checkout our subjects. Hundreds of important topics are covered in them.

Know More