Data Sheet

ADA4304-2

Rev. A | Page 9 of 10

APPLICATIONS INFORMATION

The ADA4304-2 active splitter is primarily intended for use in

the downstream path of television set-top boxes (STBs) that

contain multiple tuners. It is typically located directly after the

diplexer in a bidirectional CATV customer premise unit. The

ADA4304-2 provides a single-ended input and two single-

ended outputs that allow the delivery of the RF signal to two

different signal paths. These paths can include, but are not

limited to, a main picture tuner, the picture-in-picture (PIP)

tuner, an out-of-band (OOB) tuner, a digital video recorder

(DVR), and a cable modem (CM).

The ADA4304-2 exhibits composite second order (CSO) and

composite triple beat (CTB) products that are −62 dBc and

−72 dBc, respectively. The use of the SiGe bipolar process also

allows the ADA4304-2 to achieve a noise figure (NF) of 4 dB.

CIRCUIT DESCRIPTION

The ADA4304-2 consists of a low noise buffer amplifier followed

by a resistive power divider. This arrangement provides 2.8 dB

of gain relative to the RF signal present at the input of the device.

The input and each output must be properly matched to a 75 Ω

environment for distortion and noise performance to match the

data sheet specifications. AC coupling capacitors of 0.01 µF are

recommended for the input and outputs.

A 1 µH RF choke (Coilcraft chip inductor 0805LS-102X) is

required to correctly bias internal nodes of the ADA4304-2. It

should be connected between the 5 V supply and the IL pin

(Pin 14). The choke should be placed as close as possible to

the ADA4304-2 to minimize parasitic capacitance on the

IL pin, which is critical for achieving the specified bandwidth

and flatness.