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câu hỏi |
câu trả lời |
What is the significance of the band gap in semiconductors? bắt đầu học
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It defines the energy required to move electrons from the valence band to the conduction band, enabling conductivity.
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What is the Early effect in BJTs? bắt đầu học
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A variation in collector current due to changes in collector-base voltage, resulting in output conductance.
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What does the Miller effect refer to? bắt đầu học
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The apparent increase in input capacitance due to amplification of feedback capacitance in inverting amplifiers.
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What is channel-length modulation in MOSFETs? bắt đầu học
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A decrease in effective channel length with increased drain voltage, leading to increased drain current.
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What is transconductance (gm) in a MOSFET? bắt đầu học
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It is the rate of change of drain current with respect to gate-source voltage, gm = dId/dVgs.
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What is a differential pair used for? bắt đầu học
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To amplify the difference between two input signals while rejecting common-mode signals.
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What is the gain-bandwidth product of an op-amp? bắt đầu học
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It is the frequency at which the open-loop gain drops to unity; a key performance parameter.
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bắt đầu học
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A graph representing the gain and phase of a system as a function of frequency, used for stability and frequency response analysis.
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What is the Nyquist criterion for stability? bắt đầu học
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A graphical condition that ensures closed-loop stability by avoiding encirclements of the −1 point in the Nyquist plot.
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What is a pole in a transfer function? bắt đầu học
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A value of s where the system's response becomes infinite, related to natural frequencies and stability.
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What is a zero in a transfer function? bắt đầu học
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A frequency at which the system's output is zero despite input; used to shape response.
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What is slew rate limiting in op-amps? bắt đầu học
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A non-linear phenomenon where the output cannot change faster than a maximum rate, causing distortion.
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What does negative feedback achieve in amplifiers? bắt đầu học
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It increases linearity, reduces gain, enhances bandwidth, and improves stability.
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bắt đầu học
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The difference between the phase shift and -180° at the unity gain frequency; indicates stability.
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What is thermal runaway in BJTs? bắt đầu học
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A positive feedback condition where increased temperature leads to increased current and further heating, potentially destroying the transistor.
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What is a hysteresis loop in a Schmitt trigger? bắt đầu học
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A voltage range where input changes don't affect output, used to eliminate noise-induced switching.
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What is a Class AB amplifier's advantage over Class B? bắt đầu học
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It combines high efficiency with minimal crossover distortion.
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What is a phase-locked loop (PLL)? bắt đầu học
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A feedback system that locks the phase of an output signal to a reference, used in frequency synthesis and clock recovery.
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What is the Barkhausen criterion? bắt đầu học
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A condition for oscillation stating that the loop gain must be unity and the total phase shift must be 0 or 360°.
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What is parasitic capacitance? bắt đầu học
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Unintended capacitance that occurs between parts of an electronic component or circuit due to proximity and layout.
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