Chapter 5 (Boyleastad) - AC Analaysis

Operating Point (Q-Point)

The DC biasing point in a transistor circuit where the device operates in its intended region (cutoff, active, or saturation).

Fixed-Bias Configuration

A simple biasing method using a single resistor to provide base current, offering poor stability against variations in transistor parameters.

Emitter-Bias Configuration

A biasing scheme using a resistor in the emitter leg to improve stability by providing negative feedback.

Voltage-Divider Bias Configuration

A widely used biasing technique employing two resistors in a voltage divider network to set a stable operating point.

Collector Feedback Configuration

A biasing circuit that uses feedback from the collector to stabilize the base voltage.

Emitter-Follower Configuration

A circuit where the output follows the input voltage with unity (or near unity) gain, often used for impedance matching.

Common-Base Configuration

A BJT amplifier configuration with low input impedance, high voltage gain, and current gain less than unity.

Current Mirrors

Circuits used to copy a current from one branch to another, maintaining constant current despite load variations.

Current Source Circuits

Circuits designed to provide a constant current independent of voltage variations.

PNP Transistors

A type of bipolar junction transistor (BJT) where current flows from the emitter to the collector, opposite to NPN transistors.

Transistor Switching Networks

Circuits utilizing transistors as switches, commonly used in digital and power electronics.

Bias Stabilization

Techniques used to minimize variations in the operating point due to changes in temperature or transistor parameters.

Darlington Pair

A configuration where two BJTs are connected to provide high current gain by cascading their gain factors.

Feedback Pair

A transistor configuration similar to the Darlington pair but using a PNP-NPN combination to achieve similar results.

Hybrid Parameters (h-parameters)

A set of parameters used to model small-signal behavior in transistors, including input resistance, forward current gain, reverse voltage gain, and output admittance.

Hybrid π Model

A high-frequency small-signal model of a transistor used for analyzing AC performance.

Thévenin Equivalent Circuit

A reduced equivalent circuit that simplifies complex networks into a single voltage source and series resistance.

Load Line Analysis

A graphical method for determining a transistor’s operating point by plotting the intersection of DC bias and AC signal response.

Voltage Gain (Av)

The ratio of output voltage to input voltage in an amplifier, often expressed as Av=Vout/Vin.

Current Gain (Ai)

The ratio of output current to input current in a transistor circuit.

Input Impedance (Zi)

The resistance seen by the signal source at the input terminals of a circuit.

Output Impedance (Zo)

The resistance presented to the load at the output terminals of a circuit.

Collector-Emitter Saturation Voltage (Vce(sat))

The voltage drop across a transistor when it is fully turned on, typically low in saturation mode.

Base-Emitter On Voltage (Vbe(on))

The voltage required to turn a transistor on, typically around 0.7V for silicon BJTs.