This document is a quiz for a digital electronics circuits course. It contains 3 main sections:
1) Short answer questions about transistor switching waveforms, diode junction capacitance, logic circuits using diodes and resistors, and calculating maximum frequency for a transistor switch circuit.
2) Multiple choice questions testing knowledge of diode and transistor characteristics such as peak inverse voltage, ideal switch behavior, transistor configurations, saturation mode current amplification, and capacitor effects in transistor circuits.
3) A circuit analysis problem calculating output voltage levels at different times and determining transistor turn off time, given specifications for a circuit with a transistor, resistor, input pulse width and other parameters.
This document is a quiz for a digital electronics circuits course. It contains 3 main sections:
1) Short answer questions about transistor switching waveforms, diode junction capacitance, logic circuits using diodes and resistors, and calculating maximum frequency for a transistor switch circuit.
2) Multiple choice questions testing knowledge of diode and transistor characteristics such as peak inverse voltage, ideal switch behavior, transistor configurations, saturation mode current amplification, and capacitor effects in transistor circuits.
3) A circuit analysis problem calculating output voltage levels at different times and determining transistor turn off time, given specifications for a circuit with a transistor, resistor, input pulse width and other parameters.
This document is a quiz for a digital electronics circuits course. It contains 3 main sections:
1) Short answer questions about transistor switching waveforms, diode junction capacitance, logic circuits using diodes and resistors, and calculating maximum frequency for a transistor switch circuit.
2) Multiple choice questions testing knowledge of diode and transistor characteristics such as peak inverse voltage, ideal switch behavior, transistor configurations, saturation mode current amplification, and capacitor effects in transistor circuits.
3) A circuit analysis problem calculating output voltage levels at different times and determining transistor turn off time, given specifications for a circuit with a transistor, resistor, input pulse width and other parameters.
This document is a quiz for a digital electronics circuits course. It contains 3 main sections:
1) Short answer questions about transistor switching waveforms, diode junction capacitance, logic circuits using diodes and resistors, and calculating maximum frequency for a transistor switch circuit.
2) Multiple choice questions testing knowledge of diode and transistor characteristics such as peak inverse voltage, ideal switch behavior, transistor configurations, saturation mode current amplification, and capacitor effects in transistor circuits.
3) A circuit analysis problem calculating output voltage levels at different times and determining transistor turn off time, given specifications for a circuit with a transistor, resistor, input pulse width and other parameters.
a) Describe what causes the Turn Off time in the Transistor switching waveform. b) Define Junction Capacitance in case of a diode. c) Design a circuit using diodes and resistor to implement the following logic (A.B.C) and show in the circuit what would be the output when A=1,B=0,C=1 is applied. d) Calculate maximum frequency of square wave input that may be used in transistor switch circuit. If RB =5.6KΩ, and C=1200pF. e) Draw a circuit diagram of a direct couple inverter circuit. Provided that input is a square wave of amplitude 10 volts.
2. Choose the best answer. 8 Marks
i. For an ideal diode the peak inverse voltage(PIV) is a) infinite b) finite c) 0 d) 1 ii. The characteristics of an ideal switch is 1) When closed give infinite voltage 2) When it is open give zero current 3) When it is closed give zero voltage 4) When it is open give zero voltage drop a) 1 and 2 only b) 2 and 3 only c) 2 only c) 2 and 4 only iii. Which BJT configuration can be used as power amplifier a) Common collector b) Common emitter b) Common base d) all of the above iv. For transistor to be operated in saturation mode the current amplification factor Hfe should be a) minimum b) 100 c) infinite d) 0 v. The circuit that formed after connecting speed up/commutating capacitor in parallel w ith RB is a) Integrator circuit b) filter circuit c) Parallel circuit d) differentiator circuit vi. Storage time in diode is a) Due to majority charge carrier flow when forward bias b) Due to minority charge accumulation when forward bias c) due to internal characteristics of diode d) due to temperature coefficient of resistance of diode vii. For direct couple BJT inverter the input is a) Square wave b) pulse wave c) Sine wave d) it can be any wave viii. In design of an inverter circuit the RB is selected a) Next lower standard value than calculated b) Next higher standard value than calculated c) Calculated value can be selected d) It can be lower or higher depend on transistor
3. Solve the following numerical. 6 marks
The circuit in Figure has Vcc=12V and Rc=3.3KΩ. The input voltage has a PW of 10µs. Calculate the level of Vo. a) before input is applied, b) at the end of delay time, c) at the end of turn off time, d) Also determine the time from the commencement of the input pulse until the transistor switches off. Collector cutoff current Icex=50nA and toff =250ns