Reference no: EM131674200
Problem 1
The circuit in Fig 1 uses a potentiometer whose total resistance is R1. The movable stylus on terminal 2 creates two variable resistors: (1-β) R1 between terminals 1-2 and β R1 between terminals 2-3. The movable stylus varies β over the range 0 ≤ β ≤ 1.
Fig. 1. Circuit to be evaluated [2].
Analysis
1. Derive an expressior for gain G = vo/vs in terms of β. Show all steps and annotate as necessary.
2. Calculate the amplifier gain for β = 0.0, β = 0.5, and β =1.0 with component values R1=10kΩ and R2=1.5kΩ.
Problem 2
An Op-Amp circuit is shown below. For the ideal Op-Amp with A = ∞
a) find Vo and
b) the input impedance Ri = Vi/Ii.
c) Next assume A = 6 V/V, and repeat part a) and find Vo
Problem 3
A current amplifier is characterized by a short-circuit current gain Ai = 50, an input resistance Ri of 500, and an output resistance Ro of 2K.
Assume that the input of the current amplifier is driven by a voltage source with an open-circuit voltage Vs and a series resistance of Rs.= 250. Assume also that the output is loaded with a resistance RL of 2K. Let the output voltage be designated by Vo.
Determine the voltage gain Vo/Vs in dB.
