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REV. A

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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,

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

750⍀

10⍀

1nF

750⍀

0.01␮F

REF

0.01␮F

100⍀

10k⍀

OUT

16dBm

3.1⍀

= 100⍀

LINE-

POWER

13dBm

TRANSFORMER

1:4

10k⍀

Figure 2. Single-Supply Voltage Differential Drive Circuit

for xDSL Applications

8-Lead SOIC

(Thermal Coastline)

ⴙV

–IN2

ⴙIN2

OUT2

OUT1

–IN1

ⴙIN1

–V

AD8018AR

PIN CONFIGURATIONS

14-Lead TSSOP

OUT1

–IN1

ⴙIN1

–V

PWDN1

ⴙV

OUT2

–IN2

ⴙIN2

PWDN0

DGND

AD8018ARU

NC = NO CONNECT

LINE

– dBm

SFDR – dBc

–70

–80

–90

–60

–50

–40

–30

4186 8 10 12 14 16

N = 4.0

= 3.3V

= 5V

= 8V

Figure 1. Out-of-Band SFDR vs. ADSL Upstream Line Power;

= 5 V, N = 4 Turns, 144 kHz to 500 kHz. See Evaluation

Board Schematics in Figure 11.

Summary of content (19 pages)

PAGE 1
a 5 V, Rail-to-Rail, High-Output Current, xDSL Line Drive Amplifier AD8018 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.
PAGE 2
AD8018–SPECIFICATIONS (@ 25ⴗC, V = 5 V, R = 100 ⍀, R = R = 750 ⍀ unless otherwise noted.) S Parameter DYNAMIC PERFORMANCE –3 dB Bandwidth 0.1 dB Bandwidth Large Signal Bandwidth Slew Rate Rise and Fall Time Settling Time NOISE/HARMONIC PERFORMANCE Distortion, Second Harmonic Third Harmonic MTPR (In-Band) SFDR (Out-of-Band) Input Noise Voltage Input Noise Current Crosstalk L F G Conditions Min Typ G = 1, VOUT < 0.4 V p-p, RL = 5 Ω G = 1, VOUT < 0.4 V p-p, RL = 100 Ω G = 2, VOUT < 0.
PAGE 3
AD8018 Parameter Conditions LOGIC INPUTS (PWDN1, 0) Logic “1” Voltage Logic “0” Voltage Logic Input Bias Current Standby Recovery Time Min Typ Max Unit 2.0 V V ␮A ns 0.8 240 500 RL = 10 Ω, G = +2, IS = 90% of Typical Speciﬁcations subject to change without notice. ABSOLUTE MAXIMUM RATINGS 1 MAXIMUM POWER DISSIPATION Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 V Internal Power Dissipation2 Small Outline Package (R) . . . . . . . . . . . . . . . . . . .
PAGE 4
AD8018–Typical Performance Characteristics 1000 100 VS = ⴞ2.5V RL = 100⍀ 10␮FTANT 0.1␮F VOUT AD8018 0.1␮F VSIGNAL RLOAD 50⍀ –VS 100 INOISE – pA/ Hz ⴙVS 10 10 10␮FTANT ⴙINOISE 1 10 TPC 1. Single-Ended Test Circuit 100 1k 10k FREQUENCY – Hz 0.1 1M 100k TPC 4. INOISE and VNOISE vs. Frequency 3k 150 G=2 VS = ⴞ2.5V RL = 5⍀ VS=ⴞ2.5V 2.5k OUTPUT IMPEDANCE – ⍀ 100 OUTPUT VOLTAGE – mV 1 ⴚINOISE VNOISE – nV/ Hz (RTI) VNOISE 750⍀ 750⍀ 50 0 –50 2k (0,0) 1.
PAGE 5
AD8018 5 5 G=2 VS = ⴞ2.5V RL = 100⍀ 2 –1 –4 –7 –10 –13 –16 –4 –7 –10 –13 –16 –19 –19 –22 –22 –25 10k 100k 1M 10M FREQUENCY – Hz 100M G=2 VS = ⴞ2.5V RL = 5⍀ 2 OUTPUT VOLTAGE – dBV OUTPUT VOLTAGE – dBV –1 –25 10k 1G TPC 7. Output Voltage vs. Frequency 100k 1M 10M FREQUENCY – Hz 100M 1G TPC 10. Output Voltage vs. Frequency 2.5 4 750⍀ 750⍀ 2.4 ⴙSWING –SWING 3 VS = ⴞ2.5V 2 NORMALIZED GAIN – dB OUTPUT SWING – Volts 2.3 2.2 2.1 2.0 1.9 1.
PAGE 6
AD8018 –60 ⴙVS 10␮F VS = ⴞ2.5V G=4 fO = 100kHz VOUT = 6V p–p 0.1␮F 100⍀ 1/2 DIFFERENTIAL DISTORTION – dBc 7.96k⍀ 402⍀ 0.1␮F 500⍀ VSIGIN 50⍀ AD8018 500⍀ AD8138 500⍀ 0.1␮F 220␮F RL AD9632 0.1␮F 500⍀ 50⍀ OUT 0.1␮F ⴚ6V 25⍀ ⴙ6V 750⍀ ⴙ6V 750⍀ ⴚ6V AD8018 500⍀ 100⍀ 7.96k⍀ 1/2 –70 –80 2ND HARMONIC –90 3RD HARMONIC –100 402⍀ 10␮F ⴚVS 0.1␮F –110 5 100 10 LOAD RESISTANCE – ⍀ TPC 13. Differential Test Circuit TPC 16. Differential Distortion vs.
PAGE 7
AD8018 16 18 VS = 8.00 15 16 VS = 5.25 VS = 5.00 14 PLINE – dBm PLINE – dBm 14 13 VS = 5.00 VS = 4.75 12 VS = 4.75 VS = 4.50 12 10 11 8 VS = 3.3 3.2 3.4 3.8 4.0 4.2 4.4 3.6 TRANSFORMER TURNS RATIO 4.6 6 3.0 4.8 –20 VS = 5V RLINE = 100⍀ f = 93kHz TRANSIMPEDANCE – ⍀ MTPR – dBc P = 13dBm P = 13.5dBm P = 14dBm P = 12.5dBm P = 12dBm –60 3.6 3.8 4.0 4.2 4.4 TRANSFORMER TURNS RATIO 4.6 4.8 10M 200 1M 150 100k –40 –50 3.4 TPC 22. Line Power vs.
PAGE 8
AD8018 –10 –20 VIN = 2V p-p G=2 VS = ⴞ2.5 CROSSTALK – dB –30 –40 –50 RL = 5⍀ SIDE A DRIVEN RL = 5⍀ SIDE B DRIVEN –60 RL = 100⍀ SIDE B DRIVEN –70 –80 –90 RL = 100⍀ SIDE A DRIVEN –100 –110 100k 100M 1M 10M FREQUENCY – Hz 1G TPC 25. Crosstalk vs. Frequency THEORY OF OPERATION The AD8018 is composed of two current feedback amplifiers capable of delivering 400 mA of output current while swinging to within 0.5 V of either power supply, and maintaining low distortion.
PAGE 9
AD8018 Table I. Resistor Selection Guide ERR Gain RF (⍀) RG (⍀) –1 +1 +2 +3 +4 +5 681 1k 750 511 340 230 681 ∞ 750 256 113 59 ADP3331 OUT IN VIN C1 0.47␮F FB GND SD EOUT R3 330k⍀ R1 953k⍀ VOUT C2 0.47␮F R2 301k⍀ ON OFF Figure 6. ADP3331 LDO POWER-DOWN FEATURES Two digitally programmable logic pins, PWDN1 and PWDN0, are available on the TSSOP-14 package to select among three different modes of operation, full power, standby and shutdown. The DGND pin is the logic ground reference.
PAGE 10
AD8018 This circuit requires significant power supply bypassing. The AD8018 operates on a split supply in this circuit. The bypassing technique shown in TPC 13 utilizes a 220 µF tantalum capacitor and a 0.1 µF ceramic chip capacitor in parallel, connected from the positive to negative supply, and a 10 µF tantalum and 0.1 µF ceramic chip capacitor in parallel, connected from each supply to ground.
PAGE 11
AD8018 Following these generic guidelines will improve the performance of the AD8018 in all applications. Stability Enhancements The CPE bridge hybrid circuit presents a complex impedance to the drive amplifiers, particularly when transformer parasitics are factored in. To ensure stable operation under the full range of load conditions, a series R-C network (Zoebel Network) should be connected between each amplifier’s output and ground.
PAGE 12
AD8018 4 20 3 0 –20 VOLTS POWER – dBm 2 –40 1 0 –1 –60 –2 –3 –0.25 –80 0 50 100 FREQUENCY – kHz 150 Figure 9. DMT Waveform in the Frequency Domain –0.2 –1.5 –1.0 –0.05 0 TIME – ms 0.05 1.0 1.5 0.2 Figure 10. DMT Signal in the Time Domain MTPR versus transformer turns ratio is depicted in TPC 21 and covers a variety of line power ranging from +12 dBm to +14 dBm. As the turns ratio increases, the driver hybrid can deliver more undistorted power due to higher output current capability.
PAGE 13
AD8018 TP10 R30 0⍀ VCC-T 55 C8 0.1␮F VCC R8 100⍀ AD8018 R24 10k⍀ 2 JP4 A 1 P4 2 P4 3 B A CAPPOLY R18 750⍀ R33 10k⍀ R19 750⍀ R34 10k⍀ 10⍀ 2 1WATT 10 CAPPOLY C6 DNI C27 1000pF 1 R4 10⍀ U1 R14 100⍀ VCC-T TP4 C1 DNI AD8022 53 R17 2.49k⍀ C20 0.1␮F P3 3 P3 2 P3 R6 DNI VCC R5 DNI R7 DNI AD8022 DNI C16 DNI C3 DNI TP5 Figure 11. EVAL Board Schematic VCC R28 DNI 100⍀ R26 PDN0 JP2 U1 AD8018 100⍀ R25 JP1 0.
PAGE 14
AD8018 Figure 13. Assembly—Primary Side Figure 14. Silk Screen—Primary Side –14– REV.
PAGE 15
AD8018 Figure 15. Layer 1—Primary Side Figure 16. Layer 2—Ground Plane REV.
PAGE 16
AD8018 Figure 17. Layer 3—Power Plane Figure 18. Layer 4—Secondary Side –16– REV.
PAGE 17
AD8018 Figure 19. Assembly—Secondary Side REV.
PAGE 18
AD8018 EVALUATION BOARD—BILL OF MATERIALS Qty. Description Vendor Ref Desc. 2 2 5 2 4 3 1 1 6 2 2 5 2 3 2 2 4 2 3 4 1 2 2 1 1 4 2 4 1 2 2 1 1 4 4 1,000 pF 50 V. 1206 ceramic chip capacitor 0.01 µF 50 V. 1206 ceramic chip capacitor 0.1 µF 50 V. 1206 size ceramic chip capacitor 1.0 µF 16 V. 1206 size ceramic chip capacitor # 26 red (solid) wire jumper 10 µF 16 V. ‘C’ size Tantalum chip capacitor Ferrite bead (with # 22 wire) 10 Ω 5% 3.0 W. metal oxide power resistor 0 Ω 5% 1/8 W.
PAGE 19
AD8018 OUTLINE DIMENSIONS Dimensions shown in inches and (mm). 14 Lead TSSOP (RU-14) 0.201 (5.10) 0.197 (5.00) 0.193 (4.90) 0.1968 (5.00) 0.1890 (4.80) 8 0.1574 (4.00) 0.1497 (3.80) 5 1 0.2440 (6.20) 0.2284 (5.80) 14 0.0196 (0.50) ⴛ 45ⴗ 0.0099 (0.25) 0.0500 (1.27) BSC 0.020 (0.51) 0.013 (0.33) 8ⴗ 0.0098 (0.25) 0ⴗ 0.0075 (0.19) 0.252 (6.40) BSC 1 0.0688 (1.75) 0.0532 (1.35) SEATING PLANE 8 0.177 (4.50) 0.173 (4.40) 0.169 (4.30) PIN 1 0.0098 (0.25) 0.0040 (0.10) C01519a–.5–11/00 (rev.