REV. A
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a
AD8018
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 World Wide Web Site: http://www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 2000
5 V, Rail-to-Rail, High-Output Current,
xDSL Line Drive Amplifier
FEATURES
Ideal xDSL Line Drive Amplifier for USB, PCMCIA, or
PCI-Based Customer Premise Equipment (CPE). The
AD8018 provides maximum reach on 5 V supply,
driving 16 dBm of power into a back-terminated,
transformer-coupled 100 ⍀ while maintaining –82 dBc
of out-of-band SFDR.
Rail-to-Rail Output Voltage and High Output Current
Drive
400 mA Output Current into Differential Load of 10 ⍀
@ 8 V p-p
Low Single-Tone Distortion
–86 dBc Worst Harmonic, 6 V p-p into Differential 10 ⍀
@ 100 kHz
Low Noise
4.5 nV/√Hz Voltage Noise Density, 100 kHz
Out-of-Band SFDR = –82 dBc, 144 kHz to 500 kHz,
R
LOAD
= 12.5 ⍀, P
LINE
= 13 dBm
Low-Power Operation
3.3 V to 8 V Power Supply Range
Two Logic Bits for Standby and Shutdown
Low Supply Current of 9 mA/Amplifier (Typ)
Current Feedback Amplifiers
High Speed
130 MHz Bandwidth (–3 dB)
300 V/s Slew Rate
APPLICATIONS
xDSL USB, PCI, PCMCIA Cards
Consumer DSL Modems
Twisted Pair Line Driver
PRODUCT DESCRIPTION
The AD8018 is intended for use in single-supply (5 V) xDSL
modems where high-output current and low distortion are
essential to achieve maximum reach. The dual high-speed
amplifiers are capable of driving low distortion signals to within
0.5 V of the power supply rail. Each amplifier can drive 400 mA
of current into 10 Ω (differential) while maintaining –82 dBc
out-of-band SFDR. The AD8018 is available with flexible standby
and shutdown modes. Two digital logic bits (PWDN1 and
PWDN0) may be used to put the AD8018 into one of three
modes: full power, standby (outputs low impedance), and
shutdown (outputs high impedance).
Fabricated with ADI’s high-speed XFCB (eXtra Fast Comple-
mentary Bipolar) process, the high bandwidth and fast slew rate
of the AD8018 keep distortion to a minimum, while dissipat-
ing a minimum of power. The quiescent current of the AD8018
is a low 9 mA/amplifier. The AD8018 drive capability comes in
compact 8-lead Thermal Coastline SOIC and 14-lead TSSOP
packages. Low-distortion, rail-to-rail output voltage, and high-
current drive in small packages make the AD8018 ideal for use in
low-cost USB, PCMCIA, and PCI Customer Premise Equipment
for ADSL, SDSL, VDSL, and proprietary xDSL systems. Both
models will operate over the temperature range –40°C to +85°C.
10⍀
1nF
5V
750⍀
V
IN
10⍀
1nF
750⍀
750⍀
0.01F
0.01F
V
REF
0.01F
100⍀
100⍀
10k⍀
10k⍀
P
OUT
16dBm
R1
3.1⍀
R2
3.1⍀
R
L
= 100⍀
LINE-
POWER
13dBm
TRANSFORMER
1:4
10k⍀
10k⍀
Figure 2. Single-Supply Voltage Differential Drive Circuit
for xDSL Applications
8-Lead SOIC
(Thermal Coastline)
ⴙV
S
–IN2
ⴙIN2
6
5
7
8
OUT2
OUT1
–IN1
ⴙIN1
–V
S
1
2
3
4
AD8018AR
PIN CONFIGURATIONS
14-Lead TSSOP
OUT1
–IN1
ⴙIN1
–V
S
PWDN1
ⴙV
S
OUT2
–IN2
ⴙIN2
PWDN0
DGND
AD8018ARU
6
5
7
8
1
2
3
4
9
14
13
12
11
10
NC
NC
NC
NC = NO CONNECT
P
LINE
– dBm
SFDR – dBc
–70
–80
–90
–60
–50
–40
–30
4186 8 10 12 14 16
N = 4.0
V
S
= 3.3V
V
S
= 5V
V
S
= 8V
Figure 1. Out-of-Band SFDR vs. ADSL Upstream Line Power;
V
S
= 5 V, N = 4 Turns, 144 kHz to 500 kHz. See Evaluation
Board Schematics in Figure 11.
