Semiconductor Electronics Overview

In solids, electrons from neighboring atoms interact, creating a range of allowed energy levels instead of individual energy levels.

The band containing the valence electrons, the outermost electrons in an atom, is called the valence band.

The conduction band is the lowest unfilled energy band, where electrons can move freely and conduct electricity.

The forbidden energy gap is the energy difference between the valence band and the conduction band. Electrons cannot exist at these energy levels.

Materials that allow electrons to move freely, hence conducting electricity easily.

Materials that resist the flow of electrons, making them poor conductors of electricity.

Materials with conductivity between conductors and insulators. They can conduct electricity under certain conditions.

Insulators have a large forbidden energy gap, making it very difficult for electrons to jump from the valence band to the conduction band, hence poor conductivity.

A diode that allows current to flow in only one direction.

A rectifier that converts AC to DC by only allowing current to flow during one half of the AC cycle.

The output of a half-wave rectifier is discontinuous because current only flows during one half of the input cycle, resulting in a series of pulses.

A rectifier that converts AC to DC by using two diodes to rectify both halves of the AC cycle.

The output of a full-wave rectifier is continuous because current flows during both halves of the input cycle, resulting in a smooth DC output.

In a full-wave rectifier, the primary coil of a transformer supplies AC voltage, while the secondary coil feeds the diodes.

The load resistance R L is connected across the n-sections of the diodes in a full-wave rectifier, and the central tapping of the secondary coil.

The output of a full-wave rectifier is smoother and steadier than a half-wave rectifier because current flows consistently throughout the entire AC cycle.

A semiconductor material created by adding a small amount of trivalent impurities to a pure crystal. The majority charge carriers in a P-type semiconductor are positive holes, while the minority charge carriers are electrons.

A semiconductor created by the intimate joining of P-type and N-type materials. This junction forms due to diffusion of impurities creating a region with both positive and negative charge carriers.

A P-N junction diode is forward-biased when the positive terminal of an external DC source is connected to the P-type material, and the negative terminal is connected to the N-type material. This allows current flow through the diode.

A P-N junction diode is reverse-biased when the negative terminal of an external DC source is connected to the P-type material, and the positive terminal is connected to the N-type material. This prevents current flow across the diode.

An electronic device that transforms alternating current (AC) into direct current (DC).

A junction diode acts as a rectifier because it offers low resistance when forward biased, allowing current flow, and high resistance when reverse biased, blocking current flow.

A logic gate that inverts the output of an AND gate. It produces a high output only when both inputs are low.

A logic gate that inverts the output of an OR gate. It produces a high output only when both inputs are low.

A logic gate that can be used to implement any Boolean function without using any other logic gates.

The boolean expression for a NAND gate is Y = A * B. This means the output 'Y' is high (1) only when both inputs 'A' and 'B' are high (1).

The boolean expression for a NOR gate is Y = A + B. This means the output 'Y' is high (1) only when both inputs 'A' and 'B' are low (0).

A method of building electrical circuits using components like transistors, diodes, resistors, capacitors, and inductors, connected by soldering wires.

A type of electronic circuit that is produced by combining tiny transistors and other components on a single chip.

A process where impurities are added to a pure semiconductor material to change its conductivity.

A heavily doped P-N junction diode that operates only in reverse bias. Due to heavy doping, the depletion region is thin. When reverse bias voltage reaches the breakdown voltage, the current increases dramatically, while the voltage remains almost constant.

The reverse voltage at which a Zener diode begins to conduct a large amount of current, leading to the 'breakdown' phenomenon.

The ability of a component to maintain a constant output voltage despite fluctuations in input voltage or load current.

A semiconductor device with three sections: emitter, base, and collector. The emitter and collector have the same type of majority carriers, while the base has the opposite type.

A transistor where the emitter and collector are both n-type, and the base is p-type. The majority carriers in the emitter (electrons) are repelled towards the base due to forward bias.

The process of applying a forward bias between the emitter and base of a transistor, allowing majority carriers to flow from the emitter to the collector.

A process of applying a reverse bias between the collector and base of a transistor, forcing majority carriers to be swept away from the base and collected at the collector.

The tendency of majority carriers (electrons in an NPN transistor) to combine with minority carriers (holes in the base) within the base region.

The sum of the base current (Ib) and the collector current (Ic) equals the emitter current (Ie). This is based on Kirchhoff's first law, which states that the total current entering a junction must equal the total current leaving it.

The p-type emitter is connected to the positive pole of the emitter-base battery, creating a forward bias. Conversely, the p-type collector is connected to the negative pole of the collector-base battery, resulting in a reverse bias.

The p-type emitter is forward biased, allowing holes (majority carriers) to move from the emitter into the base region. As the base is lightly doped, most holes reach the collector and are swept away by the negative voltage of the collector-base battery.

In a common base amplifier, the base of the transistor is connected to ground, serving as a common terminal for both the emitter and collector. This configuration provides a high input resistance and a low output resistance.

The forward bias of the emitter-base circuit allows a small input voltage to control a larger output voltage across the collector-base circuit. Thus, voltage amplification occurs due to the transistor's ability to control a larger current flow in the output circuit.

During the positive half cycle of the input AC signal, the emitter-base circuit becomes more forward biased, increasing both emitter and collector current. This causes a decrease in collector voltage, making it less negative.

During the negative half cycle of the input AC signal, the emitter-base circuit becomes less forward biased, reducing both emitter and collector current. This causes an increase in collector voltage, making it more negative.

The output signal in a common base amplifier follows the same pattern as the input signal. When the input signal is positive, the output is also positive, and vice versa. This relationship is called gain, where the output voltage is amplified by a factor determined by the transistor's characteristics.