D S L / P H O N E F I LT E R S

THE INTERNETS

TALKIN’ ON THE TELEPHONE…

Image credit: http://www.accesscomms.com.au/Reference/ADSL_wiring.htm

Voice band: 0.3 - 3.4 kHzDSL band: 30 – 1104 kHz

DSL PHONE FILTER

Commercial filter What’s in the Box

L1 = 6.8 mH L2 = 10 mH C1 = 22 nF C2 = 15 pF C3 = 15 nF.

INTRODUCING INDUCTORS

In the lab On paper/In The Ether

NODAL IS POWERFUL

“Someone say Nadal is

powerful? Heck, ya, he is!”

“Settle down, Rafa.”

LOADING THE MATRIX

• Where, for convenience:

FREQUENCY SPECTRUM

-1 0 1 2 3 4 5 6 7 8 9-250

-200

-150

-100

-50

0

50

100

Frequency (Hz)

G(f

) dB

DSL phone filter

~ -80 dB/dec rolloffSteep slope!

ANOTHER DESIGN USING DIFFERENT L’S AND C’S

-1 0 1 2 3 4 5 6 7 8 9-200

-150

-100

-50

0

50

100

Frequency (Hz)

G(f

) dB

DSL phone filter: model 2

L1 = 15 mH L2 = 60 mH C1 = 10 nF C2 = 5.6 nF C3 = 2.2 nF

~ -40 dB/dec rolloff