“In the name of God”
Tutorial of ECE 340 Course
Instructor: Professor Karim
Seyyed Mojtaba Pourjaafari
Winter 2020
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5.1 The amplifier shown in Figure 1 has 𝑅𝑠𝑖𝑔 = 𝑅𝐿 = 𝑅𝐶 = 1𝑘Ω, 𝑅𝐵 = 47𝑘Ω, 𝛽 = 100, 𝐶 = 0.8 𝑝𝐹 , 𝑎𝑛𝑑 𝑓 = 600 𝑀𝐻𝑧. Assume the coupling capacitors to be very large.
𝜇𝑇
(a) Find the dc collector current of the transistor. (b)Find𝑔 and𝑟 .
𝑚𝜋
(c) Neglecting 𝑟 , find the midband voltage gain from base to collector 𝑜
(d) Use the gain obtained in (c) to find the component of 𝑅𝑖𝑛 that arises as a result of 𝑅𝐵. Hence find 𝑅𝑖𝑛.
(e) Find the overall gain at midband.
(f) Find 𝐶𝑖𝑛.
(g) Find 𝑓 . 𝐻
5.2 First consider the CS amplifier of Figure 2(a) show that 𝐴
𝑀 𝑚𝑜𝐻𝑔𝑠𝑠𝑖𝑔
= −𝑔
Where 𝐶𝐿 is the total capacitance between the output node and ground. Calculate the value of
𝐶 [𝑅 (1+𝑔 𝑟)+𝑟]+𝐶𝑟 𝑔𝑑𝑠𝑖𝑔 𝑚𝑜 𝑜 𝐿𝑜
𝐴 , 𝑓 and the gain-bandwidth product for the case 𝑔 = 1 𝑚𝐴 , 𝑟 = 20 𝑘Ω, 𝑅 = 𝑀𝐻 𝑚𝑉𝑜 𝑠𝑖𝑔
20 𝑘Ω, 𝐶 = 20 𝑓𝐹, 𝐶 = 5𝑓𝐹, and 𝐶 = 10 𝑓𝐹. 𝑔𝑠 𝑔𝑑 𝐿
(b) For the CD-CS amplifier in Figure 2(b), show that 𝐴 = − 𝑟𝑜1 (𝑔 𝑟 𝑀 1+𝑟𝑜1𝑚2𝑜2
𝑔𝑚1
)
𝑟 , 𝜏
𝑅
+
= 𝐶
2
𝑅+𝑟1
𝜏 =𝐶 𝑅 +𝐶 𝑠𝑖𝑔 𝑜1 +𝐶 ( ||𝑟 )+𝐶 [( 1 ||𝑟 )(1+𝑔 𝑟 )+𝑟 ] 𝐻 𝑔𝑑1𝑠𝑖𝑔 𝑔𝑠11+𝑔𝑟 𝑔𝑠2𝑔 𝑜1 𝑔𝑑2𝑔𝑚1𝑜1 𝑚2𝑜2 𝑜2
𝑚1 𝑜1 𝑚1
+𝐶𝑟
𝐿 𝑜2
Calculate the values of 𝐴 , 𝑓 , and the gain-bandwidth product for the same parameter values
used in (a).
𝑀𝐻
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