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For the below differential amplifier assume β = 100, VA, npn = 120 V, VA, pnp = 80 V. The Current source provides 1 uA_ of current for Q1 and Q2 not 1 mA. (a) Find the value of the current source I, if the voltage across R1 and R2 is 80 mV. (b) Calculate the small signal differential gain (Adm) for C = 0 and C = 10 pF.

For the below differential amplifier assume β = 100, VA, npn = 120 V, VA, pnp = 80 V. The Current source provides 1 uA_ of current for Q1 and Q2 not 1 mA. (a) Find the value of the current source I, if the voltage across R1 and R2 is 80 mV. (b) Calculate the small signal differential gain (Adm) for C = 0 and C = 10 pF.

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  1. For the below differential amplifier assume β = 100 , V A , npn = 120 V , V A , p n p = 80 V . The Current source provides 1 u A _ of current for Q1 and Q2 not 1 m A . (a) Find the value of the current source I , if the voltage across R 1 and R 2 is 80 m V . (b) Calculate the small signal differential gain ( A d m ) for C = 0 and C = 10 p F .

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Electronics 2 - Homework 2 Second semester 2023-2024 Solve the following questions, and verify your solution using LTSpice. simulation. For each question you need to:Solve the question by handProvide a screenshot of the circuitProvide a screenshot confirming the hand calculations Note that you can change the BJT parameter Beta by adding a SPICE directive and changing the parameter BF Question 1: BJT transistors The parameters for each transistor in the figure below are β = 80, and VBE(m) = 0.7 V. Determine all the voltages and currents in the circuit. Circuit for question 1 Question 2: Amplifier Configurations The signal source in the circuit below is vs = 5 sin⁡(100000πt)mV. The transistor parameters are β = 120, and the capacitors are 10 μF (a) Design the circuit such that IC = 0.25 mA and VCE = 3 V. (b) Find the open circuit voltage gain Avo (c) Find the input resistance Rin (from the base of the transistor) (d) Find the output resistance (e) Use the amplifier model (Avo, Rin, Ro) to find vo(t). Circuit for question 2 Question 3: Amplifier Configurations Consider the circuit shown. The transistor current gain β = 180. and the source signal has a frequency of 100 kHz and the capacitors are 10 μF Note that the current source is replaced by an open circuit in the small signal model equivalent circuit. Determine: (a) the voltage gain from source to load, (b) the input resistance seen by the source (c) the output resistance

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To improve the performance of the differential amplifier shown in Figure Q1, the biasing current source is replaced by a Widlar current source. The collector resistors are replaced by a current mirror formed by the matched bipolar transistors Qs and Q6, and the bipolar transistors Q1 and Q2 are replaced by the matched field-effect transistors M1 and M2. A single-sided output at the drain terminal of M2 is used. The transistor parameters for the bipolar transistors are: β = 100, VBE (on) = VEB(on) = 0.7 V, and VA = 100 V. The transistor parameters for M1 and M2 are: Kn = 0.15 mA/V2, VT N = 0.8 V, λ = 0.01 V-1 . The improved differential amplifier is shown in Figure Q2. (a) Determine the quiescent voltages and currents of M1 and M2 when v1 = v2 = 0. (4 marks) (b) Design the value of resistor RE such that IQ = 0.1 mA. (2 marks) (c) Determine the maximum and minimum common-mode voltages that can be applied to v1 and v2. (3 marks) (d) Determine the percentage change in IQ when the common-mode voltage applied to v1 and v2 changes from the maximum to the minimum value obtained in part (c). (5 marks) (c) Define vd = v1 - v2, determine the differential-mode voltage gain Ad of the improved differential amplifier.
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a. For the circuit shown below, show a clean and labeled small signal equivalent circuit and derive the expression for vo/vb, (vb is the small signal voltage at the base node) vo/vsig, Rin and Rout. (b) This is the design part. The specifications are as follows: The required gain vo/vb = −120 V/V, Ic = 1 mA. and the require voltage swing at the output is ±3 V around the DC value of the output. (Hint: Do not use the generic design rule. You should be able to find the DC voltages at the collector and emitter from the specifications). Assume Vcc = 8 V. For this design assume VA = ∞ (this makes ro = ∞), V T (Thermal Voltage) = 25 mV, VBE = 0.7 V, VCEsat = 0.3 V and β = ∞. Find the values of RC, RE, RB1, and RB2. (c) If the β = 100 instead of the design value, find the new Ic. Now assuming VA = 50 V find vo/vsig, Rout and RIN. For this part assume Rsig = 10 kΩ. Punt: If you could not answer (b), use RC = 3 kΩ, RE = 2 kΩ, RB1 = 50 kΩ, and RG2 = 30 kΩ (d) Run a transient simulation of the designed circuit in Multisim. Use the same BJT used in the lab simulation. Show the input voltage v sig and output voltage v o on the same plot. Choose vsig to be at 1 kHz and 10 mV peak sinusoidal. Compare with calculated value of the gain in part c.
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