2
\$\begingroup\$

What is a folded Cascode? I know what cascode topology is - but I cannot find good information about folded cascode? What is the difference?

\$\endgroup\$
3

1 Answer 1

4
\$\begingroup\$

Here is example of folded cascode amplifier [source: B. Razavi, Analog CMOS Integrated Circuits]:

enter image description here

Typical for folded cascode topology is using different branch for generating small signal currents, and different branch for generating output voltage.

In the case of the circuit from above: small signal current's are generated by M1-M2 differential pair. Current signal is then injected into M3-M4 sources and generates voltage response at the output.

We can see that small signal currents are 'folded', and hence the circuit name.

Main advantage of that topology is great swing of input voltages combined with huge gain provided by the cascode output stage.

\$\endgroup\$

Not the answer you're looking for? Browse other questions tagged or ask your own question.