BrookeECE51_14_Single-Transistors_Amplifiers

BrookeECE51_14_Single-Transistors_Amplifiers - Chapter 14...

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Unformatted text preview: Chapter 14 Single-Transistors Amplifiers Microelectronic Circuit Design Richard C. Jaeger Travis N. Blalock Chap 14 - 1 Chapter Goals • Detailed study of three broad classes of amplifiers – Inverting amplifiers- that provide high voltage gain with a 180 phase shift: common-emitter and common-source configurations, – Followers- that provide nearly unity gain similar to op amp voltage follower: common-collector and common-drain configurations, – Noninverting amplifiers- that provide medium voltage gain with no phase shift, and are wide bandwidth: common-base and common-gate configurations. • Detailed design of voltage gain, input voltage range, current gain, input and output resistances, coupling and bypass capacitor design and lower cutoff frequency for each type of amplifier. • Understand differences between SPICE ac (small-signal), transient (large-signal) and transfer function analysis modes. Chap 14 - 2 Signal Injection and Extraction: BJT • In forward-active region, • To cause change in current, v BE = v B- v E must be changed. Base or emitter terminals are used to inject signal because even if Early voltage is considered, collector voltage has negligible effect on terminal currents. • Substantial changes in collector or emitter currents can create large voltage drops across collector and emitter resistors and collector or emitter can be used to extract output. Since i B is a factor of β F smaller than i C or i E currents, base terminal is not used to extract output. = = T V BE v F S I E i T V BE v S I C i exp exp α = T V BE v FO S I B i exp β Chap 14 - 3 Signal Injection and Extraction: FET • In pinch-off region, • To cause change in current, v GS = v G- v S must be changed. Gate or source terminals are used to inject signal because even with channel-length modulation, drain voltage has negligible effect on terminal currents. • Substantial changes in drain or source currents can create large voltage drops across drain and source resistors and drain or source can be used to extract output. Since i G is always zero, gate terminal is not used to extract output. 2 2 - = = TN V GS v n K D i S i Chap 14 - 4 Amplifier Families • Constraints for signal injection and extraction yield three families of amplifiers – Common-Emitter (C-E)/Common-Source (C-S) – Common-Base (C-B)/Common-Gate (C-G) – Common-Collector (C-C)/Common-Drain (C-D) • Large Signal Amplifiers • Large enough Resistance in Common Terminal causes feedback – Common-Emitter with RE (C-EwR E )/ Common-Sourse with RS(C-SwR S ) • Large Signal Amplifiers – Others not so important: C-BwR B , C-CwR C , C-GwR G , C-DwR D ....
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This note was uploaded on 03/29/2009 for the course ECE 51 taught by Professor Martinbrooke during the Fall '08 term at Duke.

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BrookeECE51_14_Single-Transistors_Amplifiers - Chapter 14...

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