High Power, Low Distortion Upstream

CATV Line Driver

ADA4320-1

Rev. 0

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FEATURES

Supports CableLabs® DOCSIS 3.0/2.0 and EuroDOCSIS

3.0/2.0 specifications for customer premises equipment

(CPE) upstream transmission

5 V single-supply operation

Excellent adjacent channel rejection performance

−66 dBc ACPR for a single QPSK channel

−63 dBc ACPR for 4× QAM64 channels

Gain programmable in 1 dB steps over a 59 dB range

Gain range: −27 dB to +32 dB

Current-scaled output stage

Low between-burst output noise level

−70 dB mV in 160 kHz bandwidth

Maintains constant output impedance in enable, disable,

and sleep conditions

Selectable low power modes

12 mA in Tx disable

12 μA in sleep mode (full power-down)

3-wire, SPI-compatible interface

4 mm × 5 mm 24-lead LFCSP, RoHS compliant

APPLICATIONS

DOCSIS 3.0 and EuroDOCSIS cable modems/E-MTAs

DOCSIS 3.0 set-top boxes

CATV telephony modems

Coaxial or twisted pair line drivers

FUNCTIONAL BLOCK DIAGRAM

POWER

AMP

DIFF OR

SINGLE

INPUT

AMP

VERNIER

VIN–

CLK

SDATA

GND

VIN+

VOUT+

VOUT–

RAMP

ATTENUATION

CORE

DECODE

DATA LATCH

SHIFT

REGISTER

8

8

8

ADA4320-1

300Ω

POWER-DOWN

LOGIC

DATEN

TXEN

SLEEP

Figure 1.

GENERAL DESCRIPTION

The ADA4320-1 is a high power, ultralow distortion amplifier

designed for CATV reverse channel line driving. Its features and

specifications make the ADA4320-1 ideally suited for DOCSIS 3.0-

and EuroDOCSIS 3.0-based applications. Both gain and output

stage current are controlled via a 3-wire (SPI-compatible) interface.

A single 8-bit serial word selects one of four available supply

current presets and one of sixty gain codes.

The ADA4320-1 has been tailored to address both the high output

drive and stringent fidelity requirements of DOCSIS 3.0. The

part is able to maintain excellent adjacent channel rejection

performance over the full 5 MHz to 85 MHz range, even with

multiple bonded channels at maximum specified output levels.

The ADA4320-1 accepts a differential or single-ended input

signal. The output is specified for driving a single-ended 75 Ω

load through a 4:1 impedance transformer.

The ADA4320-1 features an output driver stage that scales

quiescent current consumption according to gain setting. In

multichannel mode at maximum gain (32 dB), the device draws

260 mA from a single 5 V supply, enabling the high power,

ultralow distortion performance required by multiple DOCSIS 3.0

upstream channels. For lifeline E-MTA applications, the ADA4320-1

output stage current can be throttled via SPI commands, reducing

the power requirement for single-channel transmission by up to

30%. In transmit-disable mode, the ADA4320-1 draws only 12 mA.

The device also features a full power-down sleep mode that

further reduces current draw to12 μA typical.

The ADA4320-1 is packaged in a RoHS-compliant, 24-lead

exposed pad LFCSP and is rated for operation over the −40°C

to +85°C temperature range.