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Step 13.075P (a) Refer to Figure P12 63 in the textbook for the circuit Consider =100, and =0.7 V and which are same for all Neglect base currents In other the base current of each transistor indicated with and equal zero The general expression for the emitter current (applicable to all the transistors) of simple transistor is, (since From the circuit, observed that the current mA is applied to the differential amplifier section in the circuit Due to differential circuit, the current mA divides equally to each half circuit So, the current flows through the & and section is 0.05 mA and the current flows through the and & section is 0.05 mA Step 2 of 8 The inputs are grounded and outputs are held at (by negative feedback). Also observe that the transistors & and are connected in series (that is, single half circuit). So, the collector current of The collector current of & and is, Therefore, the collector current of the each transistor and & Since the base current of transistors and Q7 is zero, then the current flows through the transistor Therefore, the collector current the transistor is, mA The base emitter voltage of the each transistor 0.7 V. the collector current of the transistor is, Since the base current =100(0) =0A Therefore, the collector current of the transistor and Step (b) The collector current though the transistor & and 50 50 From the BJT equivalent circuit, observe that the input resistance of each transistor and & Write the expression for the trans conductance Substitute 50 and 25 mV for 8m mA/V Write the expression for the 8m Substitute 100 for and mA/V for 100 Step 4 of 8 The expression for the small signal emitter resistance is, Substitute 100 for and for 100+1 {since Therefore, the input resistance of and Step 5 of 8 The collector current though the transistor is mA =1 mA From the BJT equivalent circuit, observe that the input resistance of each transistor Write the expression for the trans conductance Substitute mA and 25 mV for V1 8m =0.04 A/V Write the expression for the Substitute 100 for and A/V for 100 0.04 Step The expression for the small signal emitter resistance is, Substitute 100 for and 2.5 for {since 100+1 Therefore, the input resistance of is, The collector current though the transistor and is So, the input resistance infinite Step 7 of 8 (c) Consider the following expression 2 Substitute the corresponding 500 =4mA/V Find value =(100+1) (25)(25) 25+25 =(101)(12.46) Calculate the value gain. V/V Thus, the gain of the amplifier 5 V/V Step (d) Write the expression for the dB frequency. Substitute 100 Hz for 5 for the value 1 C= Therefore, the value of the capacitance 7.5