3.3 V DOCSIS 2.0 Upstream Cable Line Driver

The AD8324 is a low cost amplifier designed for coaxial line driving. The features and specifications make the AD8324 ideally suited for DOCSIS® 2.0 and EuroDOCSIS applications. The gain of the AD8324 is digitally controlled. An 8-bit serial word determines the desired output gain over a 59 dB range, resulting in gain changes of 1 dB/LSB.

The AD8324 accepts a differential or single-ended input signal. The output is specified for driving a 75 Ω load through a 1:1 transformer.

Distortion performance of –54 dBc is achieved with an output level up to 61 dBmV at 65 MHz bandwidth. This device has a sleep mode function that reduces the quiescent current to 30 μA and a full power-down function that reduces power-down current to 2.5 mA.

The AD8324 is packaged in a low cost, 20-lead LFCSP and a 20-lead QSOP. The AD8324 operates from a single 3.3 V supply.

Applications

* DOCSIS 2.0 and EuroDOCSIS cable modems

* CATV set-top boxes

* CATV telephony modems

* Coaxial and twisted pair line drivers

* Supports DOCSIS 2.0 and EuroDOCSIS specifications for reverse path transmission systems

* Gain programmable in 1 dB steps over a 59 dB range

* Low distortion at 61 dBmV output

* −59 dBc SFDR at 21 MHz

* −54 dBc SFDR at 65 MHz

* Output noise level at minimum gain 1.3 nV/√Hz

* Maintains 75 Ω output impedance in transmit-enable and transmit-disable condition

* Upper bandwidth of 100 MHz (full gain range)

* 3.3 V supply operation

* Supports SPI® interfaces