LTC4400-1/LTC4400-2
RF Power Controllers with
450kHz Loop BW and
45dB Dynamic Range
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FEATURES
DESCRIPTIO
RF Power Amplifier Control in ThinSOTTM Package
The LTC®4400-1 is a SOT-23 RF power controller for fast
turn-on RF power amplifiers operating in the 300MHz to
2.7GHz range. Examples include the Hitachi PF08109B,
PF08122B, PF08123B, PF08107B and RF Micro Devices
RF3108. For slow turn-on RF power amplifiers refer to the
LTC4401-1/LTC4401-2.
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Internal Schottky Diode Detector with >45dB Range
Wide Input Frequency Range:
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300MHz to 2.7GHz (LTC4400-1)
300MHz to 2GHz (LTC4400-2)
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Autozero Loop Cancels Offset Errors and
Temperature Dependent Offsets
Wide VCC Range: 2.7V to 6V
RF power is controlled by driving the RF amplifier power
control pin and sensing the resultant RF output power via
a directional coupler or capacitive tap. The RF input
voltage is peak detected using an on-chip Schottky diode.
This detected voltage is compared to the DAC voltage at
the PCTL pin to control the output power. The RF power
amplifier is protected against high power control pin
voltages.
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Automatic Bandwidth Control Improves Low Power
Ramp Response
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Allows Direct Connection to Battery
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RF Output Power Set by External DAC
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Internal Frequency Compensation
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Rail-to-Rail Power Control Output
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Power Control Signal Overvoltage Protection
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Internal and external offsets are cancelled over tempera-
ture by an autozero control loop, allowing accurate low
power programming. The shutdown feature disables the
part and reduces the supply current to <10µA.
Low Operating Current: 1mA
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Low Shutdown Current: 10µA
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Two Pole PCTL Input Filtering
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Low Profile (1mm) ThinSOT (LTC4400-1) and
8-Pin MSOP (LTC4400-2) Packages
A dual control channel version (LTC4400-2) is also
available in an 8-pin MSOP package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
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APPLICATIO S
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GSM/GPRS Cellular Telephones
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PCS Devices
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Wireless Data Modems
U.S. TDMA Cellular Phones
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LTC4400-1 Detector Characteristics at
TYPICAL APPLICATIO
900MHz and 1800MHz
10000
T
= 25°C
= 3.6V
A
V
CC
LTC4400-1 Dual Band Cellular Telephone Transmitter
1000
100
10
50Ω
900MHz
1800MHz
Li-Ion
BAND
0.1µF
6
4
3
1
5
2
0.4pF
V
RF
CC
LTC4400-1
SELECT
900MHz
OUTPUT
SHDN
V
PC
SHDN
V
PCA
900MHz
INPUT
PA MODULE
PCTL
GND
DAC
1
–26 –22–18 –14 –10 –6 –2
2
6
10 14 18
1.8GHz
OUTPUT
1.8GHz
INPUT
RF INPUT POWER (dBm)
4400 TA01
4400 TA04
sn4400 4400fas
1