AD9765AST datasheet(31/44 Pages) AD

31 / 44 page

Data Sheet

AD9763/AD9765/AD9767

Rev. G | Page 31 of 44

APPLICATIONS INFORMATION

VDSL EXAMPLE APPLICATIONS USING THE

AD9765 AND AD9767

Very high frequency digital subscriber line (VDSL) technology is

growing rapidly in applications requiring data transfer over

relatively short distances. By using quadrature amplitude

modulation (QAM) and transmitting the data in discrete multiple

tones (DMT), high data rates can be achieved.

As with other multitone applications, each VDSL tone is

capable of transmitting a given number of bits, depending on

the signal-to-noise ratio (SNR) in a narrow band around that

tone. For a typical VDSL application, the tones are evenly

spaced over the range of several kHz to 10 MHz. At the high

frequency end of this range, performance is generally limited by

cable characteristics and environmental factors such as external

interferers. Performance at the lower frequencies is much more

dependent on the performance of the components in the signal

chain. In addition to in-band noise, intermodulation from other

tones can also potentially interfere with the data recovery for

a given tone. The two graphs in Figure 79 and Figure 81

represent a 500-tone missing bin test vector, with frequencies

evenly spaced from 400 Hz to 10 MHz. This test is very

commonly done to determine if distortion limits the number of

bits that can be transmitted in a tone. The test vector has a

series of missing tones around 750 kHz, which is represented in

Figure 79, and a series of missing tones around 5 MHz, which is

represented in Figure 81. In both cases, the spurious-free

dynamic range (SFDR) between the transmitted tones and the

empty bins is greater than 60 dB.

–20

–120

–110

–100

–90

–80

–70

–60

–50

–40

–30

0.665

0.825

0.805

0.785

0.765

0.745

0.725

0.705

0.685

FREQUENCY (MHz)

Figure 79. AD9765 Notch in Missing Bin at 750 kHz Is Down >60 dB

(Peak Amplitude = 0 dBm)

–20

–120

–110

–100

–90

–80

–70

–60

–50

–40

–30

0.665

0.825

0.805

0.785

0.765

0.745

0.725

0.705

0.685

FREQUENCY (MHz)

Figure 80. AD9767 Notch in Missing Bin at 750 kHz Is Down >60 dB

(Peak Amplitude = 0 dBm)

–30

–120

–110

–100

–90

–80

–70

–60

–50

–40

4.85

4.90

4.95

5.00

5.05

5.10

5.15

FREQUENCY (MHz)

Figure 81. AD9765 Notch in Missing Bin at 5 MHz Is Down >60 dB

(Peak Amplitude = 0 dBm)

–20

–120

–100

–80

–60

–40

4.85

4.90

4.95

5.00

5.05

5.10

5.15

FREQUENCY (MHz)

Figure 82. AD9767 Notch in Missing Bin at 5 MHz Is Down >60 dB

(Peak Amplitude = 0 dBm)

AD9765AST データシート(PDF) 31 Page - Analog Devices

AD9765AST データシート(HTML) 31 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44

データシートダウンロード

リンク URL

AD9765AST データシート(PDF) 31 Page - Analog Devices

AD9765AST データシート(HTML) 31 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44

データシート ダウンロード

リンク URL

データシートダウンロード