AD9856

Rev. C | Page 34 of 36

Figure 52. PCB Lay Out Pattern for Four-Layer AD9856 PCB Evaluation Board

Layer 1 (Top)—Signal Routing and Ground Plane

Figure 53. PCB Lay Out Pattern for Four-Layer AD9856 PCB Evaluation Board

Layer 2—Ground Plane

Figure 54. PCB Lay Out Pattern for Four-Layer AD9856 PCB Evaluation Board

Layer 3—DUT +V, +5 V and 12 V Power Plane

BOT

TO

M

SI

DE

MA

DE

IN

U.

S.

A.

AD

98

56

RE

V.

C

Figure 55. PCB Lay Out Pattern for Four-Layer AD9856 PCB Evaluation Board

Layer 4 (Bottom)—Signal Routing

AD8320/21

PROGRAMMABLE

CABLE DRIVER

AMPLIFIER

ENABLE AND GAIN CONTROL BUS

75

Ω

LP FILTER

AD9856

QUADRATURE DIGITAL

UPCONVERTER

CIU CONTROL PROCESSOR

DIRECT

CONTROL

LINES

CONTROL

BUS

75

Ω

TO

75

Ω

CABLE

PLANT

UPSTREAM

TO

DOWNSTREAM

DEMODULATOR

75

Ω

DATA IN

8-20MHz

REF CLOCK IN

Figure 56. Basic Implementation of AD9856 Digital Modulator and AD8320/AD8321 Programmable Cable Driver Amplifier

in 5 MHz to 65 MHz HFC Return-Path Application

DIGITAL

OUT

DIGITAL

IN

Figure 57. Equivalent I/O Circuits