27 real Analog Electronics questions from the ECE Core bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.
1. What is Diode cut-in voltage?
Junior
A.RC oscillator using a lead-lag network in positive feedback, oscillating at 1/(2πRC) and requiring an amplifier gain of exactly 3 for audio-frequency sine output
B.forward voltage at which a junction diode begins to conduct appreciably, about 0.7 V for silicon and 0.3 V for germanium, after which current rises exponentially
C.operating region with the base-emitter junction forward biased and base-collector reverse biased, where collector current is β times base current and amplification occurs
D.capacitance between the input and output of an inverting stage appears at the input multiplied by (1 + |gain|), which sets the upper cut-off of a common-emitter amplifier
2. Which term means: "forward voltage at which a junction diode begins to conduct appreciably, about 0.7 V for silicon and 0.3 V for germanium, after which current rises exponentially"?
A.Diode cut-in voltage — RC oscillator using a lead-lag network in positive feedback, oscillating at 1/(2πRC) and requiring an amplifier gain of exactly 3 for audio-frequency sine output
B.Diode cut-in voltage — capacitance between the input and output of an inverting stage appears at the input multiplied by (1 + |gain|), which sets the upper cut-off of a common-emitter amplifier
C.Diode cut-in voltage — condition for sustained oscillation: loop gain magnitude exactly unity and total phase shift around the loop 0° or an integer multiple of 360°
D.Diode cut-in voltage — forward voltage at which a junction diode begins to conduct appreciably, about 0.7 V for silicon and 0.3 V for germanium, after which current rises exponentially
A.returning a fraction β of the output in antiphase to the input divides gain by (1 + Aβ) while extending bandwidth by the same factor and cutting distortion and drift
B.RC oscillator using a lead-lag network in positive feedback, oscillating at 1/(2πRC) and requiring an amplifier gain of exactly 3 for audio-frequency sine output
C.reverse-biased diode operated deliberately in breakdown so it holds a nearly constant voltage, serving as a shunt regulator or voltage reference
D.operating region with the base-emitter junction forward biased and base-collector reverse biased, where collector current is β times base current and amplification occurs
5. Which term means: "reverse-biased diode operated deliberately in breakdown so it holds a nearly constant voltage, serving as a shunt regulator or voltage reference"?
A.Zener diode — RC oscillator using a lead-lag network in positive feedback, oscillating at 1/(2πRC) and requiring an amplifier gain of exactly 3 for audio-frequency sine output
B.Zener diode — returning a fraction β of the output in antiphase to the input divides gain by (1 + Aβ) while extending bandwidth by the same factor and cutting distortion and drift
C.Zener diode — forward voltage at which a junction diode begins to conduct appreciably, about 0.7 V for silicon and 0.3 V for germanium, after which current rises exponentially
D.Zener diode — reverse-biased diode operated deliberately in breakdown so it holds a nearly constant voltage, serving as a shunt regulator or voltage reference
A.reverse-biased diode operated deliberately in breakdown so it holds a nearly constant voltage, serving as a shunt regulator or voltage reference
B.condition for sustained oscillation: loop gain magnitude exactly unity and total phase shift around the loop 0° or an integer multiple of 360°
C.operating region with the base-emitter junction forward biased and base-collector reverse biased, where collector current is β times base current and amplification occurs
D.returning a fraction β of the output in antiphase to the input divides gain by (1 + Aβ) while extending bandwidth by the same factor and cutting distortion and drift
8. Which term means: "operating region with the base-emitter junction forward biased and base-collector reverse biased, where collector current is β times base current and amplification occurs"?
A.BJT active region — returning a fraction β of the output in antiphase to the input divides gain by (1 + Aβ) while extending bandwidth by the same factor and cutting distortion and drift
B.BJT active region — operating region with the base-emitter junction forward biased and base-collector reverse biased, where collector current is β times base current and amplification occurs
C.BJT active region — capacitance between the input and output of an inverting stage appears at the input multiplied by (1 + |gain|), which sets the upper cut-off of a common-emitter amplifier
D.BJT active region — reverse-biased diode operated deliberately in breakdown so it holds a nearly constant voltage, serving as a shunt regulator or voltage reference
A.capacitance between the input and output of an inverting stage appears at the input multiplied by (1 + |gain|), which sets the upper cut-off of a common-emitter amplifier
B.RC oscillator using a lead-lag network in positive feedback, oscillating at 1/(2πRC) and requiring an amplifier gain of exactly 3 for audio-frequency sine output
C.BJT biasing with a base divider and emitter resistor whose negative feedback holds the Q-point nearly independent of β, provided divider resistance is well below β·RE
D.condition for sustained oscillation: loop gain magnitude exactly unity and total phase shift around the loop 0° or an integer multiple of 360°
11. Which term means: "BJT biasing with a base divider and emitter resistor whose negative feedback holds the Q-point nearly independent of β, provided divider resistance is well below β·RE"?
A.Voltage-divider bias — reverse-biased diode operated deliberately in breakdown so it holds a nearly constant voltage, serving as a shunt regulator or voltage reference
B.Voltage-divider bias — operating region with the base-emitter junction forward biased and base-collector reverse biased, where collector current is β times base current and amplification occurs
C.Voltage-divider bias — BJT biasing with a base divider and emitter resistor whose negative feedback holds the Q-point nearly independent of β, provided divider resistance is well below β·RE
D.Voltage-divider bias — condition for sustained oscillation: loop gain magnitude exactly unity and total phase shift around the loop 0° or an integer multiple of 360°
A.region where VDS exceeds VGS − Vt so the channel pinches off and drain current depends only on gate voltage, making the device a voltage-controlled current source for amplifiers
B.operating region with the base-emitter junction forward biased and base-collector reverse biased, where collector current is β times base current and amplification occurs
C.BJT biasing with a base divider and emitter resistor whose negative feedback holds the Q-point nearly independent of β, provided divider resistance is well below β·RE
D.forward voltage at which a junction diode begins to conduct appreciably, about 0.7 V for silicon and 0.3 V for germanium, after which current rises exponentially
14. Which term means: "region where VDS exceeds VGS − Vt so the channel pinches off and drain current depends only on gate voltage, making the device a voltage-controlled current source for amplifiers"?
A.MOSFET saturation region — forward voltage at which a junction diode begins to conduct appreciably, about 0.7 V for silicon and 0.3 V for germanium, after which current rises exponentially
B.MOSFET saturation region — region where VDS exceeds VGS − Vt so the channel pinches off and drain current depends only on gate voltage, making the device a voltage-controlled current source for amplifiers
C.MOSFET saturation region — reverse-biased diode operated deliberately in breakdown so it holds a nearly constant voltage, serving as a shunt regulator or voltage reference
D.MOSFET saturation region — BJT biasing with a base divider and emitter resistor whose negative feedback holds the Q-point nearly independent of β, provided divider resistance is well below β·RE
A.forward voltage at which a junction diode begins to conduct appreciably, about 0.7 V for silicon and 0.3 V for germanium, after which current rises exponentially
B.returning a fraction β of the output in antiphase to the input divides gain by (1 + Aβ) while extending bandwidth by the same factor and cutting distortion and drift
C.reverse-biased diode operated deliberately in breakdown so it holds a nearly constant voltage, serving as a shunt regulator or voltage reference
D.operating region with the base-emitter junction forward biased and base-collector reverse biased, where collector current is β times base current and amplification occurs
17. Which term means: "returning a fraction β of the output in antiphase to the input divides gain by (1 + Aβ) while extending bandwidth by the same factor and cutting distortion and drift"?
A.Negative feedback — BJT biasing with a base divider and emitter resistor whose negative feedback holds the Q-point nearly independent of β, provided divider resistance is well below β·RE
B.Negative feedback — returning a fraction β of the output in antiphase to the input divides gain by (1 + Aβ) while extending bandwidth by the same factor and cutting distortion and drift
C.Negative feedback — reverse-biased diode operated deliberately in breakdown so it holds a nearly constant voltage, serving as a shunt regulator or voltage reference
D.Negative feedback — condition for sustained oscillation: loop gain magnitude exactly unity and total phase shift around the loop 0° or an integer multiple of 360°
A.operating region with the base-emitter junction forward biased and base-collector reverse biased, where collector current is β times base current and amplification occurs
B.RC oscillator using a lead-lag network in positive feedback, oscillating at 1/(2πRC) and requiring an amplifier gain of exactly 3 for audio-frequency sine output
C.condition for sustained oscillation: loop gain magnitude exactly unity and total phase shift around the loop 0° or an integer multiple of 360°
D.BJT biasing with a base divider and emitter resistor whose negative feedback holds the Q-point nearly independent of β, provided divider resistance is well below β·RE
20. Which term means: "condition for sustained oscillation: loop gain magnitude exactly unity and total phase shift around the loop 0° or an integer multiple of 360°"?
A.Barkhausen criterion — condition for sustained oscillation: loop gain magnitude exactly unity and total phase shift around the loop 0° or an integer multiple of 360°
B.Barkhausen criterion — reverse-biased diode operated deliberately in breakdown so it holds a nearly constant voltage, serving as a shunt regulator or voltage reference
C.Barkhausen criterion — operating region with the base-emitter junction forward biased and base-collector reverse biased, where collector current is β times base current and amplification occurs
D.Barkhausen criterion — region where VDS exceeds VGS − Vt so the channel pinches off and drain current depends only on gate voltage, making the device a voltage-controlled current source for amplifiers
A.region where VDS exceeds VGS − Vt so the channel pinches off and drain current depends only on gate voltage, making the device a voltage-controlled current source for amplifiers
B.reverse-biased diode operated deliberately in breakdown so it holds a nearly constant voltage, serving as a shunt regulator or voltage reference
C.capacitance between the input and output of an inverting stage appears at the input multiplied by (1 + |gain|), which sets the upper cut-off of a common-emitter amplifier
D.operating region with the base-emitter junction forward biased and base-collector reverse biased, where collector current is β times base current and amplification occurs
23. Which term means: "capacitance between the input and output of an inverting stage appears at the input multiplied by (1 + |gain|), which sets the upper cut-off of a common-emitter amplifier"?
A.Miller effect — condition for sustained oscillation: loop gain magnitude exactly unity and total phase shift around the loop 0° or an integer multiple of 360°
B.Miller effect — capacitance between the input and output of an inverting stage appears at the input multiplied by (1 + |gain|), which sets the upper cut-off of a common-emitter amplifier
C.Miller effect — returning a fraction β of the output in antiphase to the input divides gain by (1 + Aβ) while extending bandwidth by the same factor and cutting distortion and drift
D.Miller effect — RC oscillator using a lead-lag network in positive feedback, oscillating at 1/(2πRC) and requiring an amplifier gain of exactly 3 for audio-frequency sine output
A.RC oscillator using a lead-lag network in positive feedback, oscillating at 1/(2πRC) and requiring an amplifier gain of exactly 3 for audio-frequency sine output
B.region where VDS exceeds VGS − Vt so the channel pinches off and drain current depends only on gate voltage, making the device a voltage-controlled current source for amplifiers
C.returning a fraction β of the output in antiphase to the input divides gain by (1 + Aβ) while extending bandwidth by the same factor and cutting distortion and drift
D.forward voltage at which a junction diode begins to conduct appreciably, about 0.7 V for silicon and 0.3 V for germanium, after which current rises exponentially
26. Which term means: "RC oscillator using a lead-lag network in positive feedback, oscillating at 1/(2πRC) and requiring an amplifier gain of exactly 3 for audio-frequency sine output"?
A.Wien bridge oscillator — BJT biasing with a base divider and emitter resistor whose negative feedback holds the Q-point nearly independent of β, provided divider resistance is well below β·RE
B.Wien bridge oscillator — region where VDS exceeds VGS − Vt so the channel pinches off and drain current depends only on gate voltage, making the device a voltage-controlled current source for amplifiers
C.Wien bridge oscillator — operating region with the base-emitter junction forward biased and base-collector reverse biased, where collector current is β times base current and amplification occurs
D.Wien bridge oscillator — RC oscillator using a lead-lag network in positive feedback, oscillating at 1/(2πRC) and requiring an amplifier gain of exactly 3 for audio-frequency sine output
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