LTC4401-1_15 Datasheet, PDF (1/16 Pages) Linear Technology – RF Power Controllers with 250kHz Loop BW and 45dB Dynamic Range

LTC4401-1/LTC4401-2
RF Power Controllers
with 250kHz Loop BW
and 45dB Dynamic Range
FEATURES
s _{RF Power Amplifier Control in ThinSOT}^TM _Package
s _{Internal Schottky Diode Detector with > 45dB Range}
s _{Wide Input Frequency Range:}
300MHz to 2.7GHz (LTC4401-1)
300MHz to 2GHz (LTC4401-2)
s _{Autozero Loop Cancels Offset Errors and}
Temperature Dependent Offsets
s _{Wide VCC Range: 2.7V to 6V}
s _{Automatic Bandwidth Control Improves Low Power}
Ramp Response
s _{Allows Direct Connection to Battery}
s _{RF Output Power Set by External DAC}
s _{Internal Frequency Compensation}
s _{Rail-to-Rail Power Control Output}
s _{Power Control Signal Overvoltage Protection}
s _{Low Operating Current: 1mA}
s _{Low Shutdown Current: 10µA}
s _{Two Pole PCTL Input Filtering}
s _{Low Profile (1mm) SOT-23 (ThinSOT™) (LTC4401-1)}
and 8-Pin MSOP_U(LTC4401-2) Packages
APPLICATIO S
s _{GSM/GPRS Cellular Telephones}
s _{PCS Devices}
s _{Wireless Data Modems}
s _{U.S. TDMA Cellular Phones}
DESCRIPTIO
The LTC^®4401-1 is a SOT-23 RF power controller for slow
turn-on RF power amplifiers operating in the 300MHz to
2.7GHz range. The loop bandwidth is set at 250kHz
to improve frequency stability when controlling slow
turn-on RF power amplifiers such as the Conexant
CX77301/CX77302, CX77304, CX77314, Anadigics
AWT6107 and the RF Micro Devices RF3160.
RF power is controlled by driving the RF amplifier power
control pins and sensing the resultant RF output power
via a directional coupler. The RF sense 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.
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.
A dual control channel version (LTC4401-2) 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.
TYPICAL APPLICATIO
LTC4401-1 Dual Band Cellular Telephone Transmitter
68Ω
Li-Ion
0.1µF
6
V_CC
1
RF
LTC4401-1
4
SHDN
SHDN
5
V_PCA
3
2
DAC
PCTL
GND
33pF
900MHz
INPUT
1.8GHz
INPUT
BAND
SELECT
V_PC
900MHz
OUTPUT
PA MODULE
1.8GHz
OUTPUT
50Ω
4401 TA01
4401fa
1