5 V DOCSIS 3.0 Low-distortion Upstream CATV Line Driver

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.

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

* 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