1 MHz to 1.2 GHz VGA with

30 dB Gain Control Range

ADL5331

Rev. 0

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FEATURES

Voltage-controlled amplifier/attenuator

Operating frequency: 1 MHz to 1.2 GHz

Optimized for controlling output power

High linearity: OIP3 47 dBm @ 100 MHz

Output noise floor: −149 dBm/Hz @ maximum gain

Input impedance: 50 Ω

Output impedance: 20 Ω

Wide gain-control range: 30 dB

Linear-in-dB gain control function: 40 mV/dB

Single-supply voltage: 4.75 V to 5.25 V

APPLICATIONS

Transmit and receive power control at RF and IF

CATV distribution

FUNCTIONAL BLOCK DIAGRAM

INLO

VPS1

COM1

INHI

COM2

OPLO

OPHI

IPBS

GAIN

CONTROL

BIAS

AND

VREF

GAIN

COM2

RFOUT

COM2

VPS2

VPS2

VPS2

COM1

VPS1

VPS2

VPS2

COM2

COM2

OPBS

NC

ENBL VPS2

RFIN

INPUT

GM

STAGE

OUTPUT

(TZ)

STAGE

ADL5331

Figure 1.

GENERAL DESCRIPTION

The ADL5331 is a high performance, voltage-controlled

variable gain amplifier/attenuator for use in applications with

frequencies up to 1.2 GHz. The balanced structure of the signal

path maximizes signal swing, eliminates common-mode noise

and minimizes distortion while it also reduces the risk of spu-

rious feed-forward at low gains and high frequencies caused by

parasitic coupling.

The 50 Ω differential input system converts the applied

differential voltage at INHI and INLO to a pair of differential

currents with high linearity and good common-mode rejection.

The signal currents are then applied to a proprietary voltage-

controlled attenuator providing precise definition of the overall

gain under the control of the linear-in-dB interface. The GAIN

pin accepts a voltage from 0 V at a minimum gain to 1.4 V at a

full gain with a 40 mV/dB scaling factor over most of the range.

The output of the high accuracy wideband attenuator is applied

to a differential transimpedance output stage. The output stage

provides a differential output at OPHI and OPLO, which must be

pulled up to the supply with RF chokes or a center-tapped balun.

The ADL5331 consumes 240 mA of current including the out-

put pins and operates off a single supply ranging from 4.75 V

to 5.25 V. A power-down function is provided by applying a

logic low input on the ENBL pin. The current consumption in

power-down mode is 250 μA.

The ADL5331 is fabricated on an Analog Devices, Inc., pro-

prietary high performance, complementary bipolar IC process.

The ADL5331 is available in a 24-lead (4 mm × 4 mm), Pb-free

LFCSP_VQ package and is specified for operation from ambient

temperatures of −40°C to +85°C. An evaluation board is also

available.