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For proper operation, the output terminal, that is, the drain of Q2, must be connected to a circuit that ensures that Q2 operates in saturation. 22 Circuit for a basic MOSFET constant-current sourceįigure 7.22 Circuit for a basic MOSFET constant-current source. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.ġ3 Figure 7.18 Determining the output resistant Ro of the BJT cascode amplifier.ġ4 Figure 7.19 A BJT cascode amplifier with a cascode current source.ġ5 Microelectronic Circuits, Sixth Editionġ7 Figure 7. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.ġ2 Figure 7.17 (a) A BJT cascode amplifier with an ideal current-source load (b) small-signal equivalent-circuit representation of the output of the cascode amplifier (c) the cascode amplifier with the output short-circuited to ground, and (d) equivalent circuit representation of (c). Here, a useful interpretation of the result is that Rs increases the output resistance by the factor (1 + gmRs). Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.Ħ Figure 7.11 A cascode amplifier with a cascode current-source load.ħ Microelectronic Circuits, Sixth EditionĨ Microelectronic Circuits, Sixth Editionĩ Figure 7.14 The output resistance expression of the cascode can be used to find the output resistance of a source-degenerated common-source amplifier. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.ĥ Figure 7.10 Employing a cascode transistor Q3 to raise the output resistance of the current source Q4. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.Ĥ Figure 7.9 (a) A MOS cascode amplifier with an ideal current-source load (b) equivalent circuit representation of the cascode output. Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.Ģ Microelectronic Circuits, Sixth Editionģ Figure 7.8 Determining the output resistance of the MOS cascode amplifier. 1 Microelectronic Circuits, Sixth Edition