Todays Agenda 1. Stability Problems in negative Feedback Transfer Function of the Feedback Amplifier The Nyquist Plot Effect Of Feedback On The Amplifier Poles STABILITY STUDY USING BODE PLOTS 2. Analogue IC leading to op-amp 3. Introduction to filters.

Highlights 2.3.5 Advantages and Disadvantages of negative feedback

THE STABILITY PROBLEM Transfer Function of the Feedback Amplifier The Nyquist Plot Effect Of Feedback On The Amplifier Poles STABILITY STUDY USING BODE PLOTS

Stability

Relationship between pole location and transient response.

Transfer Function of the Feedback Amplifier

The Nyquist Plot

Stable The roots are at s=-5.5 and s=-0.24±2.88j so the system is stable

Margin-Stable The roots are at s=-6 and s=±3.32j so the system is marginally stable, as expected.

Un-Stable The roots are at s=-7.5 and s=+0.75±4.64j so the system is unstable, as expected.

Relationship between pole location and transient response.

Stability using bode plot

Analogue IC leading to op-amp

One-Stage Op Amps 3

One-Stage Op Amp in Unity Gain Configuration 4

Cascode Op Amps 5

Unity Gain One Stage Cascode 6

Folded Cascode Op Amps EECE488 Set 7 - Opamp Design 7

Single-Ended Output Cascode Op Amps 13

Output Impedance Enhancement 15

Active FIlters January 2004 ENGI 242/ELEC 222 Active Filters