LTC6412 Datasheet, PDF (1/24 Pages) Linear Technology – 800MHz, 31dB Range Analog-Controlled VGA

FEATURES
n _{800MHz –3dB Small-Signal Bandwidth}
n _{Continuously-Adjustable Gain Control}
n _{–14dB to +17dB Linear-in-dB Gain Range}
n _{35dBm OIP3 at 240MHz Across All Gain Settings}
n _{10dB Noise Figure at Maximum Gain}
n _{(IIP3 – NF) = +8dBm at 240MHz Across All Gains}
n _{2.7nV/√Hz Input Referred Noise}
n _{Differential Inputs and Outputs}
n _{50Ω Input Impedance Across all Gains}
n _{Single Supply Operation from 3V to 3.6V}
n _{110mA Supply Current}
n _{4mm × 4mm × 0.75mm 24-Pin QFN Package}
APPLICATIONS
n _{IF Signal Chain Automatic Gain Control (AGC)}
n _{2.5G and 3G Cellular Basestation Transceivers}
n _{WiMAX, WiBro, WLAN Receivers}
n _{Satellite and GPS Receiver IF}
LTC6412
800MHz, 31dB Range
Analog-Controlled VGA
DESCRIPTION
The LTC^®6412 is a fully differential variable gain amplifier
with linear-in-dB analog gain control. It is designed for
AC-coupled operation in IF receiver chains from 1MHz
to 500MHz. The part has a constant OIP3 across a wide
output amplitude range and across the 31dB gain control
range. The output noise (NF + Gain) is also flat versus gain
to provide a uniform spurious-free dynamic range (SFDR)
>120dB over the full gain control range at 240MHz.
The LTC6412 is ideal for interfacing with the LT^®5527 and
LT5557 downconverting mixers, LTC6410-6 IF amplifier
and the LTC6400/LTC6401/LTC6416 ADC drivers for use
in 12-, 14-, and 16-bit ADC applications.
The LTC6412 recovers quickly from an overdrive condition,
and the EN pin allows for a fast output signal disable to
protect sensitive downstream components. Asserting the
SHDN pin reduces the current consumption below 1mA
for power-down or sleep modes.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
3.3V Fully Differential 240MHz IF Receiver Chain with 31dB Gain Control
3.3V
1nF
10nF
+IN
IF INPUT
LTC6412
–IN
10nF
3.3V
0.1μF
180nH
180nH ^3.3V
+OUT
BPF
+IN _V+ ^+OUT
0.1μF
–OUT
0.1μF
GAIN CONTROL
(+ SLOPE MODE)
LTC6400-8
V_CM
–IN V^– _–OUT
3.3V
V_DD
A_IN+
LTC2208
A_IN–
V_{CM GND}
6412 TA01
2.2μF
10nF
0.1μF
0.1μF
0.1μF
VGA Gain vs Frequency
Over Gain Control Range
20
G_MAX
10
0
–10
G_MIN
–20
–30
1
10
100
1000
FREQUENCY (MHz)
10000
6412 G01
6412f
1