Tamil Nadu HSE Second Year Basic Electronics Engineering key terms

A pure semiconductor crystal with no added impurities, in which free electrons and holes exist in equal numbers because thermal energy breaks a few covalent bonds. Its conductivity is low and rises with temperature.

The deliberate addition of small amounts of impurity atoms to a pure semiconductor to raise its conductivity. The added atoms create either extra free electrons or extra holes, depending on their valence.

A doped semiconductor containing acceptor impurities such as boron, so holes are the majority charge carriers and electrons are the minority. It remains electrically neutral overall.

A doped semiconductor containing donor impurities such as phosphorus, so free electrons are the majority carriers and holes the minority. The crystal stays electrically neutral overall.

A vacant covalent bond position in a semiconductor crystal that behaves like a positive charge carrier. Holes drift under an applied field in the direction opposite to electron flow.

The narrow zone around a PN junction that is emptied of mobile carriers, leaving fixed ionised atoms. It forms a barrier potential that must be overcome before current flows.

The voltage across the depletion region of a forward-biased junction that opposes carrier diffusion. It is about 0.7 V for silicon and 0.3 V for germanium diodes.

A heavily doped PN diode designed to operate safely in reverse breakdown. In breakdown its voltage stays nearly constant, so it is used as a voltage reference and shunt regulator.

A circuit that converts alternating current into pulsating direct current, usually using diodes. Half-wave types use one diode; full-wave and bridge types use two or four diodes.

The ratio of the AC component to the DC component of a rectifier output, indicating how much unwanted fluctuation remains. Smaller values mean smoother, better-filtered DC.

The process in a BJT where the thin, lightly doped base lets emitter-injected carriers pass to the collector, so a small base current controls a much larger collector current.

For a BJT, the ratio of collector current to base current in common-emitter connection, written beta. Typical values range from about 50 to 300.

Setting the DC voltages and currents at a transistor's terminals so it works in the desired region of its characteristics. Proper bias keeps the operating point stable despite temperature changes.

The quiescent operating point on a transistor's output characteristics, fixed by the DC bias with no signal applied. Its position decides whether the stage amplifies, switches, or distorts.

Returning a fraction of an amplifier's output signal to its input. Negative feedback reduces gain but improves stability, bandwidth, and distortion; positive feedback can cause oscillation.

For a field-effect transistor, the ratio of change in drain current to change in gate-source voltage, written gm. It measures how strongly the gate controls drain current.

The condition in a JFET or depletion MOSFET where the channel narrows until drain current saturates, no longer rising much with drain voltage. It marks the start of the constant-current region.

A node at an op-amp input that is held at almost zero volts by negative feedback, though it is not physically connected to ground. It simplifies analysis of inverting and summing circuits.

The maximum rate at which an op-amp output voltage can change, usually quoted in volts per microsecond. It limits large-signal performance at high frequencies.

An op-amp circuit run without negative feedback that compares two input voltages and swings its output to one supply rail or the other. It is used in level detection and switching.

A logic gate, namely NAND or NOR, that can build every other logic function when used alone. Circuits can therefore be made from a single gate type.

The mathematics of binary variables using AND, OR, and NOT operations. Its laws and identities let engineers simplify logic expressions and reduce the gates a circuit needs.

A grid that arranges truth-table outputs so adjacent cells differ in one variable. Grouping adjacent 1s yields a simplified sum-of-products expression without algebraic manipulation.

A combinational circuit that selects one of several data inputs and sends it to a single output, controlled by select lines. It is used for data routing and parallel-to-serial conversion.

A bistable sequential circuit that stores one bit and keeps its state until clocked or set. Types include SR, D, and JK, and they form registers and counters.

Varying a parameter of a high-frequency carrier wave in step with a message signal so it can be transmitted efficiently. Amplitude, frequency, and phase are the common parameters varied.

A number expressing how strongly a carrier is varied by the modulating signal. In AM it equals the ratio of message amplitude to carrier amplitude, and values above one cause distortion.

The process of recovering the original message from a modulated carrier at the receiver. It may use envelope detection for AM or a discriminator for FM.

A four-layer semiconductor switch that latches on once a gate pulse triggers it and then conducts until current falls below a holding value. It is widely used in phase control.

Varying the firing delay angle of a thyristor or triac within each AC cycle to adjust the average power delivered to a load. It is common in lamp dimmers and motor drives.

A circuit that holds its output voltage nearly constant despite changes in input voltage or load current. It may use a Zener diode, a series transistor, or an integrated regulator chip.

A test instrument that plots signal voltage against time on a phosphor screen, letting the user measure amplitude, period, and waveform shape directly from the trace.

A device that converts one form of energy into another, such as a thermistor changing temperature into resistance. Sensors and actuators in measurement systems are transducers.

A temperature-sensitive resistor whose resistance falls sharply as it warms, when it has a negative temperature coefficient. It is used in temperature sensing and compensation.

A single integrated circuit containing a processor, memory, and programmable input/output peripherals. It is programmed to control devices and embedded systems.

A small group of flip-flops inside a processor that holds a binary word during operations. Registers store data, addresses, and the program counter.

A dedicated computer built into a larger device to perform a specific control task, often with tight limits on cost, power, and memory. Examples include washing machines and engine controllers.