ADL5385ACPZ-R7 datasheet(15/24 Pages) AD

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Data Sheet

ADL5385

Rev. D | Page 15 of 24

BASIC CONNECTIONS

Figure 29 shows the basic connections for the ADL5385.

POWER SUPPLY AND GROUNDING

All the VPS pins must be connected to the same 5 V source.

Adjacent pins of the same name can be tied together and decoupled

with a 0.1 µF capacitor. Locate these capacitors as close as possible

to the device. The power supply can range from 4.75 V to 5.5 V.

The COM1 pin, COM2 pin, and COM3 pin are tied to the same

ground plane through low impedance paths. The exposed pad

on the underside of the package is also soldered to a low thermal

and electrical impedance ground plane. If the ground plane spans

multiple layers on the circuit board, stitch the layers together

with nine vias under the exposed pad. The Analog Devices

AN-722 Application Note discusses the thermal and electrical

grounding of the LFCSP in greater detail.

BASEBAND INPUTS

The baseband inputs QBBP, QBBN, IBBP, and IBBN must be

driven from a differential source. The nominal drive level of

1.4 V p-p differential (700 mV p-p on each pin) is biased to a

common-mode level of 500 mV dc.

The dc common-mode bias level for the baseband inputs can

range from 400 mV to 600 mV. This results in a reduction in

the usable input ac swing range. The nominal dc bias of 500 mV

allows for the largest ac swing, limited on the bottom end by the

ADL5385 input range and on the top end by the output

compliance range on most Analog Devices DACs.

LO INPUT

A single-ended LO signal is applied to the LOIP pin through

an ac coupling capacitor. The LO return pin, LOIN, must be

ac-coupled to ground though a low impedance path.

The LO input can be driven differentially, in which case the user

ac couples both sides of the differential LO source through a pair of

series capacitors to the LOIP and LOIN pins. The nominal LO

drive of −7 dBm, which is recommended, can be increased to up

to 5 dBm. For operation below 50 MHz, it is recommended to

use a minimum LO drive level of 0 dBm. The effect of LO power

on sideband suppression and carrier feedthrough is shown in

Figure 17 and Figure 21. The performance vs. LO power at

30 MHz output frequency is shown at Figure 9.

RF OUTPUT

The RF output is available at the VOUT pin (Pin 7). This pin

must also be ac-coupled. Below 150 MHz, output power decreases

due to internal ac-coupling. This is shown in Figure 8. The

VOUT pin has a nominal broadband impedance of 50 Ω and

does not need further external matching.

R22

10k

Ω

VPOS

GND

VPOS

SW21

R21

49.9

Ω OFF

VOUT

ENBL

RFPQ

Ω

RFNQ

Ω

CFPQ

OPEN

CFNQ

OPEN

QBBP

QBBN

24 VPS3

23 VPS3

22 LOIN

21 LOIP

20 COM3

19 COM3

VOUT 7

VPS1 8

VPS1 9

TEMP 10

VPS2 11

ENBL 12

ADL5385

4 × 4 LFCSP

EXPOSED PADDLE

TEMP

ENB

RTQ

OPEN

R11

Ω

RFNI

Ω

RFPI

Ω

CFNI

OPEN

CFPI

OPEN

IBBN

IBBP

RTI

OPEN

CLOP

0.1µF

CLON

0.1µF

C11

OPEN

C12

0.1µF

R12

Ω

RTEMP

200

Ω

C14

0.1µF

C13

OPEN

C16

0.1µF

C15

OPEN

COUT

0.1µF

R13

Ω

Figure 29. Basic Connections for the ADL5385

ADL5385ACPZ-R7 Datasheet(PDF) 15 Page - Analog Devices

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