(a)
A high-gain op-amp circuit shown in Figure 1a on page 2 is formed by cascading a voltage divider with a non-inverting amplifier and an inverting amplifier in series. Both op-amps are connected to 15 V power supplies. The cascade is to be designed so that the peak output voltage of the second stage comes no closer than 1V to either power supply.
IBias = 0, and Io = 0.
(i)
If both stages are in the linear region, derive the expression for the output voltage Vout including the effects of Vio in terms of R1, R2, R3, R4, R5, R6, Vin, and Vio.
(ii) Given that R1 = R2 = R and R3 = R4 = 20R and Vin is a sinusoid of 25mV, find the maximum gain of the second stage if Vout is to remain within the linear range swing limits?
Hint: The DC output voltage is negative.
(7 Marks)
R6
+15V
R1 = R
+15V
R2
R5
R3 = 20R
Vout
pAmp
15V
R4 = 20R
-15V
10
Figure 1(a)