Solving the circuit. Let's consider Vcc = 28V, Vee = -28V.
- Initially, assume that there is no saturation on OpAmps
- Check if there is negative feedback. Yes, there is negative feedback on U2 (R2). Considering the inverting amplifier formed by U2 as a black box we can assume negative feedback via R4.
- if there is neg. feedback on U1, the voltage at inverting input will be the same as non-inverting input (V1). With this is possible to calculate the current through R3. This current will be the same through R4.
- Now it's possible to calculate Vo = VR3 + Vr4 = 6.667V. If this voltage is present Vo2, Vo1 = Vo2/gain2 = 6,667/0,25 = -26,67V.
- This value is in the range of Vcc/Vee, then both OpAmp are in the linear region.
Based on: https://youtu.be/5U1xtY8t2oo
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