AD8376_1 Datasheet, PDF (1/24 Pages) Analog Devices – Ultralow Distortion IF Dual VGA

FEATURES
Dual independent digitally controlled VGAs
Bandwidth of 700 MHz (−3 dB)
Gain range: −4 dB to +20 dB
Step size: 1 dB ± 0.2 dB
Differential input and output
Noise figure: 8.7 dB @ maximum gain
Output IP3 of ~50 dBm at 200 MHz
Output P1dB of 20 dBm at 200 MHz
Dual parallel 5-bit control interface
Provides constant SFDR vs. gain
Power-down control
Single 5 V supply operation
32-lead, 5 mm x 5 mm LFCSP
APPLICATIONS
Differential ADC drivers
Main and diversity IF sampling receivers
Wideband multichannel receivers
Instrumentation
GENERAL DESCRIPTION
The AD8376 is a dual channel, digitally controlled, variable gain
wide bandwidth amplifier that provides precise gain control,
high IP3, and low noise figure. The excellent distortion perform-
ance and high signal bandwidth make the AD8376 an excellent
gain control device for a variety of receiver applications.
Using an advanced high speed SiGe process and incorporating
proprietary distortion cancellation techniques, the AD8376
achieves 50 dBm output IP3 at 200 MHz.
The AD8376 provides a broad 24 dB gain range with 1 dB
resolution. The gain of each channel is adjusted through
dedicated 5-pin control interfaces and can be driven using
standard TTL levels. The open-collector outputs provide a
flexible interface, allowing the overall signal gain to be set by
the loading impedance. Thus, the signal voltage gain is directly
proportional to the load.
Each channel of the AD8376 can be individually powered on by
applying the appropriate logic level to the ENBA and ENBB
power enable pins. The quiescent current of the AD8376 is
typically 130 mA per channel. When powered down, the
Ultralow Distortion IF Dual VGA
AD8376
FUNCTIONAL BLOCK DIAGRAM
A4 A3 A2 A1 A0
VCCA GNDA
IPA+
IPA–
VCMA
VCMB
IPB+
IPB–
CHANNEL A
GAIN
DECODER
α
α
CHANNEL B
GAIN
DECODER
AD8376
POST-AMP
POST-AMP
OPA+
OPA+
OPA–
OPA–
ENBA
ENBB
OPB+
OPB+
OPB–
OPB–
B4 B3 B2 B1 B0
VCCB
Figure 1.
GNDB
AD8376 consumes less than 5 mA and offers excellent input-to-
output isolation, lower than −50 dB at 200 MHz.
Fabricated on an Analog Devices, Inc., high speed SiGe process,
the AD8376 is supplied in a compact, thermally enhanced,
5 mm × 5mm 32-lead LFCSP package and operates over the
temperature range of −40°C to +85°C.
–40
65
–50
60
–60
55
OIP3
–70
50
–80
–90
–100
45
HD2
40
HD3
35
–110
30
40 60
80 100 120 140 160 180 200
FREQUENCY (MHz)
Figure 2. Harmonic Distortion and Output IP3 vs. Frequency
Rev. A
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