CIRCUITS AND ELECTRONICS. Filters

Transcription

1 6.00 IUITS AND EETONIS Flters te as: Anant Agarwal and Jeffrey ang, course materals for 6.00 rcuts and Electroncs, Sprng 007. MIT 6.00 Fall 000 ecture 8

2 evew v I v c c c j j j eadng: Secton 4.5, 4.6, 5.3 from A &. te as: Anant Agarwal and Jeffrey ang, course materals for 6.00 rcuts and Electroncs, Sprng 007. MIT 6.00 Fall 000 ecture 8

3 A Flter c c j ( ) H c ow Pass Flter Demo wth audo te as: Anant Agarwal and Jeffrey ang, course materals for 6.00 rcuts and Electroncs, Sprng 007. MIT 6.00 Fall 000 ecture 8

4 Quck evew of Impedances- Just as A I ab B ab ab AB Iab A I ab j B ab ab AB I ab j te as: Anant Agarwal and Jeffrey ang, course materals for 6.00 rcuts and Electroncs, Sprng 007. MIT 6.00 Fall 000 ecture 8

5 Quck evew of Impedances Smlarly A B AB j j te as: Anant Agarwal and Jeffrey ang, course materals for 6.00 rcuts and Electroncs, Sprng 007. MIT 6.00 Fall 000 ecture 8

6 We can buld other flters by combnng mpedances ( ) te as: Anant Agarwal and Jeffrey ang, course materals for 6.00 rcuts and Electroncs, Sprng 007. MIT 6.00 Fall 000 ecture 8

7 We can buld other flters by combnng mpedances ( ) H ( ) H ( ) HPF Hgh Pass Flter PF ow Pass Flter H ( ) HPF te as: Anant Agarwal and Jeffrey ang, course materals for 6.00 rcuts and Electroncs, Sprng 007. MIT 6.00 Fall 000 ecture 8

8 heck out: r Intutvely: r r r blocks low freq j j j j o ( ) ( ) te as: Anant Agarwal and Jeffrey ang, course materals for 6.00 rcuts and Electroncs, Sprng 007. MIT 6.00 Fall 000 ecture 8 blocks hgh freq At resonance, o and 0, so sees only! More later

9 What about: lc lc Band Stop Flter open open heck out l and c n the lab. te as: Anant Agarwal and Jeffrey ang, course materals for 6.00 rcuts and Electroncs, Sprng 007. MIT 6.00 Fall 000 ecture 8

10 Another example: o o BPF short o short Applcaton: see AM rado comng up shortly te as: Anant Agarwal and Jeffrey ang, course materals for 6.00 rcuts and Electroncs, Sprng 007. MIT 6.00 Fall 000 ecture 8

11 AM ado ecever antenna demodulator amplfer Thévenn antenna model crystal rado demo te as: Anant Agarwal and Jeffrey ang, course materals for 6.00 rcuts and Electroncs, Sprng 007. MIT 6.00 Fall 000 ecture 8

12 AM ecever demodulator amplfer sgnal strength 0 KHz flter WB News ado f KHz Selectvty mportant relates to a parameter Q for the flter. Next te as: Anant Agarwal and Jeffrey ang, course materals for 6.00 rcuts and Electroncs, Sprng 007. MIT 6.00 Fall 000 ecture 8

13 Selectvty: ook at seres n more detal r ecall, r r j Δ bandwdth j hgher Q o Defne o Q Δ hgh Q qualty factor more selectve te as: Anant Agarwal and Jeffrey ang, course materals for 6.00 rcuts and Electroncs, Sprng 007. MIT 6.00 Fall 000 ecture 8

14 Qualty Factor Q Q o Δ ο : r j j j o at ο 0 Δ? te as: Anant Agarwal and Jeffrey ang, course materals for 6.00 rcuts and Electroncs, Sprng 007. MIT 6.00 Fall 000 ecture 8

15 Δ : Qualty Factor Q Q o Δ Note that abs magntude s r when j.e. when ± ± j 0 ookng at the roots of both equatons, 4 4 Δ te as: Anant Agarwal and Jeffrey ang, course materals for 6.00 rcuts and Electroncs, Sprng 007. MIT 6.00 Fall 000 ecture 8

16 Qualty Factor Q Q o Δ o o Q o The lower the (for seres ), the sharper the peak te as: Anant Agarwal and Jeffrey ang, course materals for 6.00 rcuts and Electroncs, Sprng 007. MIT 6.00 Fall 000 ecture 8

17 Qualty Factor Q Another way of lookng at Q : energy stored Q π energy lost per cycle π Q o I r I r π 0 te as: Anant Agarwal and Jeffrey ang, course materals for 6.00 rcuts and Electroncs, Sprng 007. MIT 6.00 Fall 000 ecture 8