AD8392A

Rev. 0 | Page 10 of 12

MULTITONE POWER RATIO

The DMT signal used in ADSL/ADSL2+ systems carries data in

discrete tones or bins, which appear in the frequency domain in

evenly spaced 4.3125 kHz intervals. In applications using this

type of waveform, multitone power ratio (MTPR) is a commonly

used measure of linearity. MTPR is defined as the measured

difference from the peak of one tone that is loaded with data to

the peak of an adjacent tone that is intentionally left empty.

Figure 19 and Figure 20 show the AD8392A MTPR for a 5.5

crest factor waveform for empty bins in the ADSL and extended

ADSL2+ bandwidths.

0

–100

CENTER 646.9kHz

SPAN 10kHz

–10

–20

–30

–40

–50

–60

–70

–80

–90

Figure 19. MTPR at 647 kHz

0

–100

CENTER 1.9664kHz

SPAN 10kHz

–10

–20

–30

–40

–50

–60

–70

–80

–90

Figure 20. MTPR at 1.966 MHz