A current controlled current source (CCCS) has an input impedance of 10 Ω and output impedance of 100 kΩ. When

Q. A current controlled current source (CCCS) has an input impedance of 10 Ω and output impedance of 100 kΩ. When this CCCS is used in a negative feedback closed loop with a loop gain of 9, the closed loop output impedance is

(A) 10 Ω

(B) 100 Ω

(C) 100 kΩ

(D) 1000 kΩ

Ans: 1000 kΩ

Solution:

Input impedance = 10 Ω

Output impedance = 100 kΩ

loop again (Aβ) = 9

Closed loop impedance will be:

Z_out = Z_o [1 + Aβ]

= 100 × 10³ [1 + 9]

= 1000 kΩ