Question

Given that capacitance w.r.t the input node is 2pF and output node is 4pF, find capacitance between input and output node.

(a) 0.67 pF

(b) 1.34pF

(c) 0.44pF

(d) 2.2pF

This question was posed to me in an online quiz.

I want to ask this question from Low Frequency Response and Miller Effect Capacitance in portion Transistor Frequency Response of Analog Circuits

Answer 1

Right option is (a) 0.67 pF

The best explanation: C1=C(1-K), C2=C(1-K^-1)

C1=2pF

C2=4pF

C1/C2=1/2=1-K/1-K-1

K = -2

C1 = C(1+2) = 3C

C = C1/3 = 2/3pF = 0.67 pF.