Electronic Circuits and Applications Flashcard Deck

Comprehensive vocabulary flashcards covering semiconductor materials, PN junctions, various diode types, BJT and FET configurations, operational amplifiers, and thyristors based on EE4002 lecture notes.

Conductors

Materials that conduct electricity easily due to a high density of free charge carriers, with examples including copper, silver, and gold.

Semiconductors

Materials whose electrical conductivity lies between conductors and insulators, such as silicon $(Si)$, germanium $(Ge)$, and gallium arsenide $(GaAs)$, which can be manipulated by heat or doping.

Doping

The process of adding controlled impurities to an intrinsic semiconductor to drastically increase conductivity by increasing the number of current carriers like electrons or holes.

N-type semiconductor

A material created by adding pentavalent impurities $(As, P, Bi, Sb)$ with 5 valence electrons, where electrons are the majority carriers and holes are the minority carriers.

P-type semiconductor

A material created by adding trivalent impurities $(B, In, Ga)$ with 3 valence electrons, where holes are the majority carriers and electrons are the minority carriers.

Depletion Region

A region around a PN junction empty of free charge carriers containing fixed positive and negative ions that set up an electric field.

Potential Barrier

The voltage of the electric field across the depletion region that must be overcome for conduction, typically $0.7\,V$ for silicon and $0.3\,V$ for germanium at $25^{\circ}C$.

Thermal Voltage $(V_T)$

A term in Shockley's diode equation that is approximately $26\,mV$ at room temperature.

Dynamic (AC) Resistance $(r_d)$

The slope of the I-V curve at a specific operating point, calculated as $r_d \approx \frac{26\,mV}{I_D}$.

Varactor (Varicap)

A diode used as a voltage-variable capacitor that operates in reverse bias, where the depletion region serves as the dielectric.

Electroluminescence

The process by which an LED produces light when forward-biased electrons cross the junction and recombine with holes, releasing energy as photons.

Photodiode

A diode designed to operate in reverse bias where the reverse current increases proportionally with light intensity $(irradiance)$, except for a tiny dark current.

Schottky Diode

A high-speed switching diode formed by a metal-to-semiconductor junction with a low forward voltage drop of approximately $0.3\,V$.

PIN Diode

A diode featuring an intrinsic $(I)$ region between heavily doped P and N regions, acting as a current-controlled variable resistance when forward-biased.

Tunnel Diode

A heavily doped diode with an extremely narrow depletion region that exhibits negative resistance, where current falls as voltage rises.

Diode Limiter (Clipper)

A circuit that removes portions of a signal above or below a specific level by conducting when the diode becomes forward-biased.

Half-wave Rectifier Average Output

The average DC voltage produced from a half-wave rectifier, calculated as $V_{AVG} = \frac{V_P}{\pi} \approx 0.318 V_P$.

Full-wave Rectifier Average Output

The average DC voltage produced when both half-cycles are used, calculated as $V_{AVG} = \frac{2V_P}{\pi} \approx 0.637 V_P$.

Ripple Factor $(r)$

The ratio of peak-to-peak ripple voltage to the DC output voltage $(r = \frac{V_{r(pp)}}{V_{DC}})$, representing the residual fluctuation in a filtered DC output.

Zener Diode

A diode designed to operate in reverse breakdown at a stable Zener voltage $(V_Z)$ without damage, used for voltage regulation.

BJT (Bipolar Junction Transistor)

A three-terminal device using both electrons and holes as charge carriers, typically used for amplification and switching.

Alpha DC $(\alpha_{DC})$

The ratio of collector current to emitter current $(\frac{I_C}{I_E})$, typically ranging between $0.95$ and $0.99$.

Voltage-Divider Bias

A common BJT biasing configuration that provides high stability by making the operating point largely independent of $\beta$ variations.

Common-Collector (Emitter-Follower)

An amplifier stage with a voltage gain of approximately 1, high input impedance, and low output impedance, often used as a buffer.

JFET (Junction Field-Effect Transistor)

A voltage-controlled transistor with extremely high input impedance where the gate-channel junction is always reverse-biased.

Pinch-off Voltage $(V_P)$

The value of $V_{DS}$ at which the depletion regions in a JFET channel nearly meet, causing the drain current to saturate.

Enhancement-Type MOSFET

A field-effect transistor that has no physical channel at $V_{GS} = 0$ and requires a threshold voltage $(V_T)$ to create a conducting channel.

Common-Mode Input

A condition in a differential amplifier where the same signal is applied to both inputs simultaneously.

Hysteresis

A technique using positive feedback in a comparator to create upper and lower trigger points, preventing erratic switching due to noise.

Sustained Oscillation Conditions

The requirements for an oscillator: a net phase shift of $0^{\circ}$ around the loop and a loop gain of exactly 1.

SCR (Silicon Controlled Rectifier)

A gate-triggered thyristor that acts as a latching switch, remaining on until the anode current falls below the holding current $(I_H)$.

DIAC

A bidirectional two-terminal thyristor equivalent to back-to-back four-layer diodes that conducts once break-over voltage is reached in either polarity.

TRIAC

A bidirectional gate-triggered device equivalent to two SCRs in inverse parallel, used for AC phase control.