22圖示電路,若 VCC = 9 V、RC = 2 kΩ、RB = 100 kΩ,電晶體之 β= 100,VBE = 0.7 V,今若電晶體工作在主動區(active region)與飽和區(saturation region)之交界;VCE(sat)=0.2 V,則電壓 VBB 約為何?