Low Frequency to 3 GHz, Dual VGA with

Output Common-Mode and DC Offset Control

Data Sheet

ADRF6521

Rev. 0

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FEATURES

Dual, matched VGAs

Maximum voltage gain: 18 dB

±1 dB gain flatness bandwidth: 2.5 GHz typical

IMD2 and IMD3 (1.5 V p-p output level)

−56.8 dBc typical and −75 dBc typical, respectively, at VGN =

1.5 V, 980 MHz and 1000 MHz tones

HD2 and HD3 (1.5 V p-p output level)

−75 dBc typical and −73.7 dBc typical, respectively, at VGN =

1.5 V, fundamental at 500 MHz

−55.9 dBc typical and −57.5 dBc typical, respectively, at

VGN = 1.5 V, fundamental at 1 GHz

Noise figure

10.5 dB typical at maximum gain and at 500 MHz

14.8 dB at maximum gain and at 2 GHz

Noise figure decreases dB for dB with gain backoff

100 Ω differential input impedance

≤16 Ω differential output impedance

Programmable

Output DC offset nominal range: ±400 mV

Output common-mode control: > ±200 mV for VOCM = ±0.2 V

Single- or dual-supply operation with power-down feature

Single supply: VPOS = 5 V, VNEG = 0 V (nominal)

Dual supply: VPOS = 3 V, VNEG =−2 V (nominal)

APPLICATIONS

Point-to-point and point-to-multipoint radios

Baseband IQ receivers

Diversity receivers

ADC drivers

Instrumentation

Medical

SIMPLIFIED FUNCTIONAL BLOCK DIAGRAM

18dB

+ –

– +

VPOS

VGN

VNEG

FLT1

OFS1

OPM1

OPP1

VOCM

18dB

OPP2

OPM2

VPOS

PWD

VNEG

FLT2

OFS2

INM1

INP1

COMM

INP2

INM2

ADRF6521

+ –

– +

Figure 1.

GENERAL DESCRIPTION

The ADRF6521 is a dual, fully differential, low noise and low

distortion variable gain amplifier (VGA). The high spurious-

free dynamic range over the gain range makes the ADRF6521

ideal for communication systems with dense constellations,

multiple carriers, and nearby interferers.

The VGA has a 21 dB attenuation range with a typical voltage

gain of 18 dB. The differential input impedance is 100 Ω, while the

differential output impedance is 16 Ω. The ±1 dB gain flatness

bandwidth is 2.5 GHz. The output buffers are capable of swinging

1.5 V p-p into 100 Ω loads at >55 dBc for second-order and

third-order intermodulation distortion (IMD2 and IMD3), and

for second and third harmonic distortion (HD2 and HD3) from

low frequency to 1 GHz. Variable output dc offset control is

accomplished with the OFS1 and OFS2 pins, and the output

common-mode can be controlled with the VOCM pin.

The ADRF6521 flexibly operates from a single +5 V supply or

from a range of dual supplies and consumes a total supply

current of 200 mA. When fully disabled, it consumes 25 mA

typical. The ADRF6521 is fabricated in an advanced silicon-

germanium BiCMOS process and is available in a 20-lead,

exposed pad, 3 mm × 3 mm LFCSP. Performance is specified

over the −40°C to +85°C temperature range.