课程名称︰数位电子学 课程性质︰系必修 课程教师︰顾孟恺 开课学院：电资学院 开课系所︰资工系 考试日期（年月日）︰2010.4.26 考试时限（分钟）：180 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : Digital Electronics Midterm Instructor: Mong-Kai Ku 4/26/2010 Grading: Total 100 points 1. --------+Vcc----------- | | Amplification | | ↓ I1 ↓I2 PTAT voltage generator→Amplification→A/Dconverter | | →Digital scaling and offset | | →Display ↓ ↓ _ _ | | _______________________ | _(ground) - (a)(10%)Please mark the two points for(mark for correct polarity) voltage proportional to absolute temperature in the above figure and derive the equation for PTAT voltage. (b)Assume VFS = 1.0V for A/D converter, I1 = 10I2, and we want to measure from 0K to 600K. (1)(5%)What is amplification factor A to fully utilize the A/D converter? (2)(5%)What is the accuracy of this thermometer? 2.(10%)Use current and voltage division to find I1,I2 and V3 in the current in Fig.1 if I = 5mA, R1 = 2.4kΩ, R2 = 5.6Ω, R3 = 3.6Ω ---------------I2→----------- | | | | ↓I1 R2 ↑I R1 R3 + | | | V3 ----------------------------- - Fig.1 3.(10%)Draw a two-dimensional conceptual pecture of the silicon lattice containing one donor atom and two acceptor atom in adjacent lattice positions . Are there any free electrons or hole? 4. (a)(10%)At what temperature will ni = 10^13/cm^3 in silicon? (b)(10%)A silicon wafer is uniformly doped with 5.5 x 10^16 phosphorus atoms/cm^3 and 4.5 x 10^16 boron atoms/cm^3. Find the electron and hole concentrations, the electron and hole mobilities, and the resistivity of this silicon material at 300K. Is this material n- or p-type? Temperature(K) 500 333 250 200 Intrinsic carrier density(cm^-6) 10^16 10^14 Germanium 10^12 10^10 10^8 Silicon 10^6 10^2 Gallium arsenide 10^0 Reciprocal temperature(1000/T) 2 3 4 5 B(K^-3xcm^-6) EG(eV) Si 1.08x10^31 1.12 Ge 2.31x10^30 0.66 GaAs 1.27x10^29 1.42 5.(20%)What is maximum load current IL that can be drawn from the Zener regulator in Fig.5 if it is to maintain a regulated output? What is the minimum value of RL that can be used and still have a regulated output voltage? -----15kΩ--------→IL----------- | | | + ↑(Zener) | VZ = 9V 27V | RL RZ = 0 - | | | | | --------------------------------- Figure 5 6.(20%)Find the Q-point for the diodes in the circuits in Fig.6 using the constant voltage drop model with Von = 0.6 V. 0V ↓ | +10V--→--3.3kΩ-----6.8kΩ------------2.4kΩ---- -5V | ↑ | +5V Figure 6 --

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