ADL5331

Rev. 0 | Page 14 of 16

INTERFACING TO AN IQ MODULATOR

The basic connections for interfacing the ADL5331 with the

ADL5385 are shown in Figure 24. The ADL5385 is an RF

quadrature modulator with an output frequency range of

50 MHz to 2.2 GHz. It offers excellent phase accuracy and

amplitude balance, enabling high performance direct RF

modulation for communication systems.

The output of the ADL5385 is designed to drive 50 Ω loads and

easily interfaces with the ADL5331. The input to the ADL5331

can be driven single-ended, as shown in Figure 17. Similar

configurations are possible with the ADL537x family of

quadrature modulators. These modulators can provide outputs

from 500 MHz to 4 GHz.

SOLDERING INFORMATION

On the underside of the chip scale package, there is an exposed

compressed paddle. This paddle is internally connected to the

chip’s ground. Solder the paddle to the low impedance ground

plane on the printed circuit board to ensure specified electrical

performance and to provide thermal relief. It is also recom-

mended that the ground planes on all layers under the paddle

be stitched together with vias to reduce thermal impedance.

10nF

10nF

INHI

INLO

RF OUTPUT

10nF

10nF

OPHI

COMM

VPOS

OPLO

5V

5V

ETC1-1-13

LO

IBBP

IBBN

QBBP

QBBN

COMM

VPOS

5V

GAIN CONTROL

100pF

100pF

DIFFERENTIAL I/Q

BASEBAND INPUTS

DAC

DAC

VOUT

ADL5385

IQ MOD

68µH

68µH

ADL5331

RF VGA

Figure 24. ADL5385 Quadrature Modulator and ADL5331 Interface