Calculate the VI – VO for the level shifter shown in the figure (Assume identical silicon transistor and very large value of β). Transistor QA and QB form current mirror.
Calculate the VI – VO for the level shifter shown in the figure (Assume identical silicon transistor and very large value of β). Transistor QA and QB form current mirror. Correct Answer 6.65v
Since the transistor QA and QB form current mirror, ICA= ICB = I. => I = (VCC – VBE) / R0 = (15v-0.7)/12k Ω (for β>>1, output current =input current) => I= 1.19mA. The shift in level is given as VI – VO = VBE + I×R1 =0.07v+1.19mA×5kΩ =6.65v.
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Feb 20, 2025
