1 Feedback

Microelectronic Circuits - Fifth Edition Sedra/Smith2 Copyright  2004 by Oxford University Press, Inc. Figure 8.1 General structure of the feedback amplifier. This is a signal-flow diagram, and the quantities x represent either voltage or current signals.

Microelectronic Circuits - Fifth Edition Sedra/Smith3 Copyright  2004 by Oxford University Press, Inc. Figure E8.1

Microelectronic Circuits - Fifth Edition Sedra/Smith4 Copyright  2004 by Oxford University Press, Inc. Figure 8.1 General structure of the feedback amplifier. This is a signal-flow diagram, and the quantities x represent either voltage or current signals. A ~ open loop gain of the amplifier  ~ feedback ratio x s ~ signal from source x o ~ output signal x f ~ feedback signal x i ~ input signal to amplifier

Microelectronic Circuits - Fifth Edition Sedra/Smith5 Copyright  2004 by Oxford University Press, Inc. Figure 8.1 General structure of the feedback amplifier. This is a signal-flow diagram, and the quantities x represent either voltage or current signals. x f =  x o x i = x s - x f x o =  x i x o =  x s - x f ) x o =  x s - A  x o )  )  x o = A x s Gain with Feedback: Closed Loop Gain  ~ loop gain

Microelectronic Circuits - Fifth Edition Sedra/Smith6 Copyright  2004 by Oxford University Press, Inc. Figure 8.1 General structure of the feedback amplifier. This is a signal-flow diagram, and the quantities x represent either voltage or current signals. Gain Desensitivity

Microelectronic Circuits - Fifth Edition Sedra/Smith7 Copyright  2004 by Oxford University Press, Inc. Figure 8.1 General structure of the feedback amplifier. This is a signal-flow diagram, and the quantities x represent either voltage or current signals. Bandwidth Extension

Microelectronic Circuits - Fifth Edition Sedra/Smith8 Copyright  2004 by Oxford University Press, Inc. Figure 8.1 General structure of the feedback amplifier. This is a signal-flow diagram, and the quantities x represent either voltage or current signals. Bandwidth Extension

Microelectronic Circuits - Fifth Edition Sedra/Smith9 Copyright  2004 by Oxford University Press, Inc. Figure 8.1 General structure of the feedback amplifier. This is a signal-flow diagram, and the quantities x represent either voltage or current signals. Bandwidth Extension

Microelectronic Circuits - Fifth Edition Sedra/Smith10 Copyright  2004 by Oxford University Press, Inc. Figure 8.2 Illustrating the application of negative feedback to improve the signal-to-noise ratio in amplifiers. Noise Reduction

Microelectronic Circuits - Fifth Edition Sedra/Smith11 Copyright  2004 by Oxford University Press, Inc. Figure 8.2 Illustrating the application of negative feedback to improve the signal-to-noise ratio in amplifiers. Noise Reduction Superposition:

Microelectronic Circuits - Fifth Edition Sedra/Smith12 Copyright  2004 by Oxford University Press, Inc. Figure 8.2 Illustrating the application of negative feedback to improve the signal-to-noise ratio in amplifiers. Noise Reduction

Microelectronic Circuits - Fifth Edition Sedra/Smith13 Copyright  2004 by Oxford University Press, Inc. Reduction in Nonlinear Distortion x f =  x o x i = x s - x f x o =  x i + x nl x o =  x s - x f ) + x nl x o =  x s - A  x o ) + x nl  )  x o = A x s + x nl

Microelectronic Circuits - Fifth Edition Sedra/Smith14 Copyright  2004 by Oxford University Press, Inc. Figure 8.4 The four basic feedback topologies: (a) voltage-mixing voltage-sampling (series–shunt) topology; (b) current-mixing current-sampling (shunt–series) topology; (c) voltage-mixing current-sampling (series–series) topology; (d) current-mixing voltage-sampling (shunt–shunt) topology.

Microelectronic Circuits - Fifth Edition Sedra/Smith15 Copyright  2004 by Oxford University Press, Inc. Effects of Negative Feedback on Input and Output Impedances

Microelectronic Circuits - Fifth Edition Sedra/Smith16 Copyright  2004 by Oxford University Press, Inc.

Microelectronic Circuits - Fifth Edition Sedra/Smith17 Copyright  2004 by Oxford University Press, Inc.

Microelectronic Circuits - Fifth Edition Sedra/Smith18 Copyright  2004 by Oxford University Press, Inc.

Microelectronic Circuits - Fifth Edition Sedra/Smith19 Copyright  2004 by Oxford University Press, Inc.