1. 1 Slides taken from: A.R. Hambley, Electronics, © Prentice Hall, 2/e, 2000 Frequency Response. Part D – Amplifiers at Low Frequency

2. 2 Amplifiers at low frequencies Capacitors affecting the low frequency behavior of an amplifier: Coupling capacitors By-pass capacitors Load capacitance

3. 3 Load Capacitance Figure 8.46 The load capacitance C L and the output resistance R o form a low-pass filter.

4. 4 Figure 8.47 Amplifier with coupling capacitors. Coupling Capacitors

5. 5 Figure 8.48 Magnitude Bode plot for the amplifier of Figure 8.47. (We have assumed that f 1 > f 2.) Effect of Coupling Capacitors

6. 6 Figure 8.53 Example: Discrete common-emitter amplifier. Bypass Capacitors

7. 7 Effect of the Bypass Capacitor

8. 8 Figure 8.54 Gain magnitude versus frequency. Effect of the Bypass Capacitor

9. 9 Coupling vs. Bypass

10. 10 Approximate determination of the break frequencies

11. 11 Approximate determination of the break frequencies

12. 12 Approximate determination of the break frequencies

13. 13 Approximate determination of the break frequencies