For the BJT transistor circuit given in the Figure 3 below, Vcc = +10 V and the transistor's AC current gain, hFE = 250. Figure 3: BJT switching circuit a. Calculate the values of RB and RC that will ensure that the transistor operates efficiently as a switch for the input waveform Vin as shown above (use E12 resistor value). Sketch the output waveform that will result from the given input waveform. Use transistor DC gain, βDC = 250. [20 marks] b. Calculate the Q-point if a constant value of input voltage, Vin = 3 V is applied at the input. Determine if this design is feasible and, if it is not, suggest a solution to fix it? [10 marks]
![For the BJT transistor circuit given in the Figure 3 below, Vcc = +10 V and the transistor's AC current gain, hFE = 250. Figure 3: BJT switching circuit a. Calculate the values of RB and RC that will ensure that the transistor operates efficiently as a switch for the input waveform Vin as shown above (use E12 resistor value). Sketch the output waveform that will result from the given input waveform. Use transistor DC gain, βDC = 250. [20 marks] b. Calculate the Q-point if a constant value of input voltage, Vin = 3 V is applied at the input. Determine if this design is feasible and, if it is not, suggest a solution to fix it? [10 marks]](https://www.doubtrix.com/uploads/editor/5946860013KJrJyuEcKs.jpg)
![The figure below shows a circuit that consists of two BJTs. Both transistors Q1 and Q2 are constructed with similar geometry and design parameters. The supply voltage, Vcc = 7 V, and the value of the resistor, R, is 6.3 kohm. Assume all the transistors are biased in the active region with similar current gain, B = 100, and base-emitter voltage, VBE = 0.7 V. (a) State the type of the circuit shown above. [3 marks] (b) State one disadvantage of using BJT compared to MOSFET in this application. [3 marks] (c) Determine the collector current of transistor Q2. [5 marks] (d) Determine the collector current of transistor Q1. [4 marks] (e) Explain the cause of the mismatch between the input reference current, IR, and the output current, IC1. [5 marks] (f) Suggest a circuit topology that reduces the mismatch between the input reference current and the output current. Sketch and label the suggested circuit. Use only BJTs in your proposed circuit. [5 marks]](https://www.doubtrix.com/js/ckeditor/filemanager/connectors/php/editor/1695265632-Q288.png)
![(a) Assume that the MOSFET in Figure 3.1 is operating in saturation and is characterised by a threshold voltage, VT = 1 V. Assume that the parameter, K = 1 mA/V2 where the drain-source current in the MOSFET in saturation is given by the usual expression: iDS = K2(vGS−VT)2 Calculate the output voltage, vo, for the circuit shown in Figure 3.1 when vIN = 2.5 V, Vs = 10 V, and R = 1 kΩ. The correct solution should satisfy both conditions necessary for the device to operate in saturation. Figure 2.1 [10 marks] (b) For the circuit in Figure 2.1, calculate the small signal voltage gain of the circuit, Av, at the operating point defined by the numerical values of part (a). Assume the input and output voltages include small signal components, vin and vout respectively. VIN and Vout correspond to the constant DC components of the input and output voltage from part (a). vIN = VIN +vin vOUT = VOUT +vout Av = vout vin [10 marks] (c) Determine the small signal output impedance at the terminals labelled a and b for the circuit shown in Figure 3.1 and at the operating point defined by the numerical values of part (a). [10 marks]](https://www.doubtrix.com/uploads/editor/3475428305cJOidAHSIp.jpg)
![A full-wave bridge rectifier circuit is shown in Fig. 2(a) with a "floating" signal generator and grounded load resistor, which is the most common configuration of this rectifier. Its output waveform appears in Fig. 2 b. Note that the output frequency is twice the input frequency, but the time period T and angular period 2π on the horizontal axis refer to the input waveform. Following a similar development to the halfwave rectifier, the dc output voltage from the full-wave bridge rectifier is given by: Vavg = 1π∫θ1 θ2[Vmsin(θ) − 2Vd]dθ Where, the integration is over half the original waveform's period and the 2Vd term is due to the load current flowing through two diodes. The peak output voltage is vo, peak = Vm − 2Vd. The integration limits are found using Eq. 5 with the angles referred to the original input waveform. θ1 = sin−1(2Vd/Vm) and θ2 = π − θ1 However, the full-wave rectifier's conduction angle must be referred to the output waveform's period, which is half that of the input so φ = 2(θ1−θ2). (a) (b) Fig. 2. (a) Full-wave bridge rectifier circuit and (b) output waveform. Perform the following calculations for the full-wave rectifier in Fig. 2. Put your results in Table 1. a. Determine vo,peak, θ1, and θ2 for the rectifier output waveform of Fig. 2 b. b. Calculate the average (dc) value of vo(t) using Eq. 4 . c. Calculate the conduction angle φ.](https://www.doubtrix.com/uploads/editor/6776072514rhzokOtWGl.png)