mid_term_solution_2007

# mid_term_solution_2007 - Solution to Problem 1 Part A 5V...

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Solution to Problem 1 5 V L C 1 + - C 2 C 3 R 1 R 2 Port 1 Port 2 T Part A Inductor L acts as RF choke and is used for preventing RF signal from leakage to the bias network and allowing DC current flowing into transistor. (0.5) Capacitors C1 and C2 are used to isolate DC bias of transistor T and other component between the RF signal and allowing RF signal flowing into transistor. (0.5+0.5) Capacitors C3 acts as RF ground and are used for isolation between the RF signal and the DC supply. (0.5) The resistors R2 is used for bias the base of transistor and stabilize the bias conditions if current gain changes. (0.5) The resistors R1 are used for bias the collector of transistor and limit the maximum current flowing into transistor T. (0.5)

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Current Gain: Solution to Problem 1 5 V L C 1 + - C 2 C 3 R 1 R 2 Port 1 Port 2 T Part A ( ) 1 cc b c CE V I I R V = + + 2 20 3 0.7 100 m R = + ce b b be V I R V = + 1 20 5 20 3 100 m m R = + + By KVL, By KVL, c b I I β = 1 99.0 R = Ω 2 11.5 R K = Ω Check: R>>50 Ω , therefore it can be directly connected to the transmission line (0.5) (0.5) (0.5) (0.5)