solids

1. In a p+np bipolar transistor circuit, grounded base circuit, α=0.99. The in" rel="nofollow">input circuit has a battery voltage of 1 V. Assume the in" rel="nofollow">input diode turns on at 0.6V(i.e. no IE until 0.6V, after that the diode current in" rel="nofollow">increases vertically without resistance) .The series resistance in" rel="nofollow">in the in" rel="nofollow">input circuit is 100 ohm. The output circuit has a battery voltage of 40 V, and a load resistance in" rel="nofollow">in the output is 1k ohm. Draw the dc Q conditions for both in" rel="nofollow">input and output. What is the DC Q poin" rel="nofollow">int current and voltage in" rel="nofollow">in the output collector-base circuit? Draw a load lin" rel="nofollow">ine curve for the in" rel="nofollow">input and output. Show the in" rel="nofollow">intersection poin" rel="nofollow">ints for both. 2. In the above transistor, if Wb=1 micrometer, and the dopin" rel="nofollow">ing in" rel="nofollow">in the base is 2E17/cm3, and base and collector are equally doped, at what battery voltage in" rel="nofollow">in the CB circuit will the device break down? The Avalanche field is 5E5 V/cm. 3. In the transistor of #2, if I reduce the base and collector dopin" rel="nofollow">ing to 1E16/cm3, at what battery voltage in" rel="nofollow">in the CB circuit will the transistor break down? 4. In problem 1, now I overdrive the transistor by reducin" rel="nofollow">ing series resistance in" rel="nofollow">in the in" rel="nofollow">input circuit. [That drives more current in" rel="nofollow">in the in" rel="nofollow">input and therefore in" rel="nofollow">in the output circuit]. Assume that saturation occurs when Vcb flips sign and become +0 .4V. What must the new series resistance in" rel="nofollow">in the in" rel="nofollow">input circuit be to achieve this? Assume that until then, α=0.99. 5. MOSFET amplifier. n channel. VT=1V. VGS=3 V. Z/L=40. Mobility=500 cm2/V-s. Cox=3.45E-7 F/cm2. Battery voltage in" rel="nofollow">in the output circuit= 40 V. RG (in" rel="nofollow">in the gate circuit)=100 ohm. RL in" rel="nofollow">in the output circuit =2k. A small ac voltage is in" rel="nofollow">in the in" rel="nofollow">input circuit. i) Draw the dc and ac equivalent circuits ii) Draw the I-V curve on the output. Show the value of the saturation knee- poin" rel="nofollow">int. Show the load lin" rel="nofollow">ine and in" rel="nofollow">intersection(Q) poin" rel="nofollow">int. Calculate the Q poin" rel="nofollow">int values for current(IDS) and voltage(VDS) iii) Calculate trans-conductance gm. iv) Calculate the amplification factor. 6. Now I use the MOSFET of #5 as a logic gate – in" rel="nofollow">inverter. Assume that the I-V curve only has two regions-lin" rel="nofollow">inear from 0V to knee poin" rel="nofollow">int for saturation, and then saturation I value (two straight lin" rel="nofollow">ines). Usin" rel="nofollow">ing this approximation, draw IDS vs. VDS curves (to scale) for values of VGS in" rel="nofollow">increasin" rel="nofollow">ing by 1 V from 0V. A family of curves will result- 5 in" rel="nofollow">in all. Label each one with the VGS value. What is the value of the output voltage when the MOSFET is used as an in" rel="nofollow">inverter with VGS= 4V? What is the current?