Data Sheet

ADCA3992

Rev. 0 | Page 7 of 9

THEORY OF OPERATION

The ADCA3992 is a 75 Ω input and output matched module

designed for CATV applications. The ADCA3992 uses cascode

field effect transistor (FET) feedback amplifiers in a Class A

push pull configuration. The bottom half of the cascode stages

are implemented in a single-die linear FET process that

minimizes parasitics, thereby enabling higher gain. The top

devices in the cascodes are implemented using a linear GaN

process that is able to swing very high RF voltages. The

frequency of operation is from 45 MHz to 1218 MHz.

Internally, the ADCA3992 module uses a balun to convert the

input signal to a balanced signal that feeds the active stages. An

output impedance transformer and balun combination converts

the balanced GaN signals into an unbalanced 75 Ω output. The

output transformer also feeds the dc to the active stages and

cancels second-order distortion products coming from the

active devices.

The module has a control pin (IADJ) to set the dc current

consumption from low bias to the full bias of the device by

connecting a resistor from this pin to ground or by using a

positive voltage.

75Ω

75Ω

BIAS

CONTROL

Figure 9. Simplified Schematic