Bipolar Junction Transistors: Types, Construction, Operation, and Applications - Prof. Bre, Study notes of Electrical and Electronics Engineering

Download Bipolar Junction Transistors: Types, Construction, Operation, and Applications - Prof. Bre and more Study notes Electrical and Electronics Engineering in PDF only on Docsity! Online Resource for ETCH 213 Faculty: B. Allen Bipolar Junction Transistors Online Resource for ETCH 213 Faculty: B. Allen Transistor types NPN Transistor – A thin, highly doped p-type region (base) is sandwiched between two n-type regions (emitter and collector). PNP Transistor – A thin, highly doped n-type region (base) is sandwiched between two p-type regions (emitter and collector). Online Resource for ETCH 213 Faculty: B. Allen Transistor construction and packaging Online Resource for ETCH 213 Faculty: B. Allen Transistor operation Transistors are basically controlled to operate as a switch, or are controlled to operate as a variable resistor. Online Resource for ETCH 213 Faculty: B. Allen ON/OFF switching Online Resource for ETCH 213 Faculty: B. Allen Transistor as a digital logic gate Online Resource for ETCH 213 Faculty: B. Allen Transistor as an analog amplifier Amplification – Boosting in strength, or increasing amplitude, of an electronic signal. Online Resource for ETCH 213 Faculty: B. Allen Input-output voltage waveforms Online Resource for ETCH 213 Faculty: B. Allen Basic switching regulator action Online Resource for ETCH 213 Faculty: B. Allen Emitter Current (IE) – The current at the transistor’s emitter terminal. Base Current (IB) – The relatively small current at the transistor’s base terminal. Collector Current (IC) – The current emerging out of the transistor’s collector. IE = IB + IC EC II ≅ Online Resource for ETCH 213 Faculty: B. Allen Current-controlled transistor As IB IC and IE Online Resource for ETCH 213 Faculty: B. Allen Biasing PNP bipolar transistors Use negative base voltage. Use negative collector voltage. Online Resource for ETCH 213 Faculty: B. Allen Bipolar transistor configurations Configurations – Different circuit interconnections. Common – Shared by two or more services, circuits, or devices. Although the term “common ground” is frequently used to describe two or more connections sharing a common ground, the term common alone does not indicate a ground connection, only a share connection. Online Resource for ETCH 213 Faculty: B. Allen A correctly biased PNP transistor circuit Online Resource for ETCH 213 Faculty: B. Allen Online Resource for ETCH 213 Faculty: B. Allen Active Region – Flat part of the collector’s characteristic curve. A transistor is normally operated in this region, where it is equivalent to a variable resistor between the collector and emitter. Quiescent Operating Point (Q-point) – The voltage or current values that set up the no input signal or operating point bias voltage. Common-emitter circuits (cont.) Online Resource for ETCH 213 Faculty: B. Allen Common-emitter circuits (cont.) Breakdown Region – The point at which the collector supply voltage will cause a damaging value of current through the transistor. Saturation region – The point at which the collector supply voltage has the transistor operating in saturation. Cutoff region – The point at which the collector supply voltage has the transistor operating in cutoff. Online Resource for ETCH 213 Faculty: B. Allen Common-Base configuration (continued) DC Alpha (αDC) – The ratio for calculation a C-B transistor’s dc current gain. AC Alpha (αAC) – The ratio of the input emitter current change to the output collector current change in a C-B transistor Power gain in a C-B transistor configuration AP = AV × αAC E C DC I I =α E C AC I I ∆ ∆ =α Online Resource for ETCH 213 Faculty: B. Allen Common-Collector (C-C) configuration A configuration in which the input signal is applied between the transistor’s base and collector, while the output is developed across the transistor’s collector and emitter. Online Resource for ETCH 213 Faculty: B. Allen C-C (continued) DC current gain = IE/IB DC current gain = 1 + βDC Since βDC = IC/IB Online Resource for ETCH 213 Faculty: B. Allen C-C as an impedance matching circuit Impedance Matching Circuit – A circuit that can match, or isolate, a high resistance (low current) source. Buffer Current Amplifier – The C-C circuit that can ensure that power is efficiently transferred from the source to the load. Online Resource for ETCH 213 Faculty: B. Allen Bipolar data sheet Online Resource for ETCH 213 Faculty: B. Allen Testing bipolar junction transistors Transistor Tester – A special test instrument that can be used to test both NPN and PNP bipolar transistors. Online Resource for ETCH 213 Faculty: B. Allen Base biasing Base Biasing – A transistor biasing method in which the dc supply voltage is applied to the base of the transistor via a base bias resistor VBE = 0.7V Online Resource for ETCH 213 Faculty: B. Allen DC load line DC Load Line – A line representing all the DC operating points of a transistor for a given load resistance. Online Resource for ETCH 213 Faculty: B. Allen Typical dc load line with Q point