Before revision: In contrast, using the active load of Figure 2, the AC impedance of the ideal current source is infinite regardless of the voltage drop VCC - Vout, which allows even a large value of VCB.
After revision: In contrast, using the active load of Figure 2, the AC impedance of the ideal current source is infinite regardless of the voltage drop VCC − Vout, which allows even a large value of VCB.