Data Sheet

ADCA5190

APPLICATIONS INFORMATION

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Rev. 0 | 17 of 22

DOWNSTREAM APPLICATIONS CIRCUIT WITH

PASSIVE BIASING

The schematic in Figure 31 and the PCB layout in Figure 34 are

recommended for downstream cable system applications from 45

MHz to 1800 MHz that employ passive biasing. Recommended

values for all components are in the BOM listed in Table 10. T1

is an RF transformer configured to transform the single-ended 75

Ω RF input to a differential signal that drives the 37.5 Ω inputs

of the ADCA5190 (RFIN and RFIP). The voltage at Pin 1 of E2

this reference and serves as the ac ground for the RF input signal.

Capacitor C29 between the FBN pins (Pin 14 and Pin 16) provides

feedback for the negative side of the amplifier, and Capacitor C30

between the FBP pins (Pin 25 and Pin 27) provides feedback for

the positive side of the amplifier.

T2 is an RF transformer configured to transform the differential 37.5

Ω outputs (RFON and RFOP) to a single-ended 75 Ω RF output.

The C3, C5, C7, C8, C13, C14, C18, C20, L8, L9, L10, and

L11 components are intended for impedance matching, and these

components must be optimized to match the RF input source and

RF output load. Capacitor C4 blocks the dc voltage of the RF input

source. Capacitor C27 and Capacitor C28 block the dc voltage at

the RFOP (Pin 22 and Pin 23) and RFON (Pin 18 and Pin 19)

output pins. The L2 and L3 inductors are RF chokes connected to

Figure 31. Suggested Downstream Cable TV (CATV) Application Circuit with Passive Biasing Schematic