Cascode gain stage

Used in order to prevent the Miller effect

 

Q₂ used to isolate the input and output nodes

Low input resistance at its source and high resistance at its drain to drive Q₃

 

For low frequencies:

 

Overall voltage gain can be large

Capacitance between the input and output terminals can be neglected
                                                                      ... no significant Miller effect

 

Gain can be increased by using a depletion-mode load device