LTC4401-1/LTC4401-2
RF Power Controllers
with 250kHz Loop BW
and 45dB Dynamic Range
FEATURES
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DESCRIPTIO
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RF Power Amplifier Control in ThinSOT
TM
Package
Internal Schottky Diode Detector with > 45dB Range
Wide Input Frequency Range:
300MHz to 2.7GHz (LTC4401-1)
300MHz to 2GHz (LTC4401-2)
Autozero Loop Cancels Offset Errors and
Temperature Dependent Offsets
Wide V
CC
Range: 2.7V to 6V
Automatic Bandwidth Control Improves Low Power
Ramp Response
Allows Direct Connection to Battery
RF Output Power Set by External DAC
Internal Frequency Compensation
Rail-to-Rail Power Control Output
Power Control Signal Overvoltage Protection
Low Operating Current: 1mA
Low Shutdown Current: 10µA
Two Pole PCTL Input Filtering
Low Profile (1mm) SOT-23 (ThinSOT™) (LTC4401-1)
and 8-Pin MSOP (LTC4401-2) Packages
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.
APPLICATIO S
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GSM/GPRS Cellular Telephones
PCS Devices
Wireless Data Modems
U.S. TDMA Cellular Phones
TYPICAL APPLICATIO
LTC4401-1 Dual Band Cellular Telephone Transmitter
68Ω
33pF
Li-Ion
0.1µF
6
V
CC
LTC4401-1
SHDN
4
SHDN
V
PCA
5
V
PC
900MHz
INPUT
1.8GHz
INPUT
900MHz
OUTPUT
RF
1
BAND
SELECT
3
DAC
PCTL
GND
2
PA MODULE
1.8GHz
OUTPUT
50Ω
4401 TA01
U
4401fa
U
U
1
LTC4401-1/LTC4401-2
ABSOLUTE
AXI U
RATI GS
V
CC
to GND .............................................. – 0.3V to 6.5V
V
PCA/B
Voltage to GND ............................ – 0.3V to 3.2V
PCTL Voltage to GND ................. – 0.3V to (V
CC
+ 0.3V)
RF Voltage to GND ............................ (V
CC
– 2.6V) to 7V
BSEL, SHDN Voltage to GND ...... – 0.3V to (V
CC
+ 0.3V)
PACKAGE/ORDER I FOR ATIO
TOP VIEW
RF 1
GND 2
PCTL 3
6 V
CC
5 VPCA
4 SHDN
ORDER PART
NUMBER
LTC4401-1ES6
S6 PART MARKING
LTXA
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
T
JMAX
= 125°C,
θ
JA
= 230°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
PARAMETER
V
CC
Operating Voltage
I
VCC
Shutdown Current
I
VCC
Operating Current
V
PCA/B
V
OL
V
PCA/B
Dropout Voltage
V
PCA/B
Voltage Clamp
V
PCA/B
Output Current
V
PCA/B
Enable Time
V
PCA/B
Bandwidth
V
PCA/B
Load Capacitance
V
PCA/B
Slew Rate
V
PCA/B
Droop
V
PCA/B
Start Voltage
BSEL, SHDN Input Threshold
BSEL, SHDN Input Current
PCTL Input Voltage Range
PCTL Input Resistance
PCTL Input Filter
Autozero Range
(Note 4)
Open Loop (Note 9)
V
CC
= 2.7V to 6V
BSEL = SHDN = 3.6V
(Note 7)
SHDN = 0V
SHDN = HI, I
VPCA/B
= 0mA
R
LOAD
= 400Ω, Enabled
I
LOAD
= 6mA, V
CC
= 3V
PCTL = 1V
V
PCA/B
= 2.4V, V
CC
= 3V
SHDN = V
CC
(Note 5)
CONDITIONS
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 3.6V, SHDN = HI, unless otherwise noted.
MIN
q
q
q
q
q
q
q
q
C
LOAD
= 100pF, R
LOAD
= 2k (Note 8)
(Note 6)
V
PCTL
= 2V Step, C
LOAD
= 100pF,
R
LOAD
= 400Ω (Note 3)
2
U
U
W
W W
U
W
(Note 1)
I
VPCA/B
.................................................................. 10mA
Operating Temperature Range (Note 2) .. – 30°C to 85°C
Storage Temperature Range ................ – 65°C to 150°C
Maximum Junction Temperature ......................... 125°C
Lead Temperature (Soldering, 10 sec)................. 300°C
TOP VIEW
V
CC
V
PCA
V
PCB
GND
1
2
3
4
8
7
6
5
RF
BSEL
SHDN
PCTL
ORDER PART
NUMBER
LTC4401-2EMS8
MS8 PART MARKING
LTXC
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 250°C/W
TYP
10
1.2
MAX
6
20
1.9
0.05
V
CC
– 0.25
UNITS
V
µA
mA
V
V
V
mA
µs
kHz
kHz
pF
V/µs
µV/ms
2.7
0
2.7
7
175
2.9
10
9
250
130
1.5
1
3.1
10.2
330
100
PCTL < 80mV
PCTL > 160mV
q
q
q
1
2
q
q
q
q
q
300
0.35
16
0
60
450
24
90
270
550
1.4
36
2.4
120
400
mV
V
µA
V
kΩ
kHz
mV
4401fa
q
LTC4401-1/LTC4401-2
ELECTRICAL CHARACTERISTICS
PARAMETER
RF Input Frequency Range
RF Input Power Range
(LTC4401-1)
CONDITIONS
LTC4401-1 (Note 6)
LTC4401-2 (Note 6)
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 3.6V, SHDN = HI, unless otherwise noted.
MIN
300
300
–28
–26
–24
–22
–28
–26
q
TYP
MAX
2700
2000
18
18
16
16
18
18
UNITS
MHz
MHz
dBm
dBm
dBm
dBm
dBm
dBm
Ω
RF Frequency = 900MHz (Note 6)
RF Frequency = 1800MHz (Note 6)
RF Frequency = 2400MHz (Note 6)
RF Frequency = 2700MHz (Note 6)
RF Frequency = 900MHz (Note 6)
RF Frequency = 2000MHz (Note 6)
Referenced to V
CC
RF Input Power Range
(LTC4401-2)
RF Input Resistance
150
250
350
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
The LTC4401-X is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the – 30°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3:
Slew rate is measured open loop. The slew time at V
PCA/B
is
measured between 1V and 2V.
Note 4:
Maximum DAC zero-scale offset voltage that can be applied to
PCTL.
Note 5:
This is the time from SHDN rising edge 50% switch point to
V
PCA
= 0.25V.
Note 6:
Guaranteed by design. This parameter is not production tested.
Note 7:
Includes maximum DAC offset voltage and maximum control
voltage.
Note 8:
Bandwidth is calculated using the 10% to 90% rise time:
BW = 0.35/rise time
Note 9:
Measured 12µs after SHDN = HI.
TYPICAL PERFOR A CE CHARACTERISTICS
PCTL REFERENCED DETECTOR OUTPUT VOLTAGE (mV)
PCTL REFERENCED DETECTOR OUTPUT VOLTAGE (mV)
PCTL REFERENCED DETECTOR OUTPUT VOLTAGE (mV)
LTC4401-1 Detector Characteristics
at 900MHz
10000
75°C
25°C
–30°C
1000
100
10
1
–28
–22 –16 –10 –4
2
8
RF INPUT POWER (dBm)
U W
14
LTC4401-1 Detector Characteristics
at 1800MHz
10000
75°C
25°C
–30°C
LTC4401-1 Detector Characteristics
at 2400MHz
10000
75°C
25°C
–30°C
1000
1000
100
100
10
10
1
–26 –20
–14 –8
–2
4
10
RF INPUT POWER (dBm)
16
4401 G02
1
–24 –20 –16 –12 –8 –4 0 4 8
RF INPUT POWER (dBm)
12 16
4401 G03
4401 G01
4401fa
3
LTC4401-1/LTC4401-2
TYPICAL PERFOR A CE CHARACTERISTICS
PCTL REFERENCED DETECTOR OUTPUT VOLTAGE (mV)
PCTL REFERENCED DETECTOR OUTPUT VOLTAGE (mV)
10000
10000
PCTL REFERENCED DETECTOR OUTPUT VOLTAGE (mV)
LTC4401-1 Detector Characteristics
at 2700MHz
75°C
25°C
–30°C
1000
100
10
1
–22 –18 –14 –10 –6 –2 2 6
RF INPUT POWER (dBm)
PI FU CTIO S
(LTC4401-1/LTC4401-2)
RF (Pins 1/8):
RF Feedback Voltage from the Directional
Coupler. Referenced to V
CC
. A coupling capacitor of 33pF
must be used to connect to the ground referenced direc-
tional coupler. The frequency range is 300MHz to 2700MHz
for the LTC4401-1 and 300MHz to 2000MHz for the
LTC4401-2. This pin has an internal 250Ω termination, an
internal Schottky diode detector and peak detector capaci-
tor.
GND (Pins 2/4):
System Ground.
PCTL (Pins 3/5):
Analog Input. The external power control
DAC drives this input. The amplifier servos the RF power
until the RF detected signal equals the DAC signal. The
input impedance is typically 90kΩ.
V
PCB
(Pin 3): (LTC4401-2 Only)
Power Control Voltage
Output. This pin drives an external RF power amplifier
power control pin. The maximum load capacitance is
100pF.
4
U W
LTC4401-2 Detector Characteristics
at 900MHz
75°C
25°C
–30°C
LTC4401-2 Detector Characteristics
at 1800MHz
10000
75°C
25°C
–30°C
1000
1000
100
100
10
10
10 14
4401 G04
1
–28
–22 –16 –10 –4
2
8
RF INPUT POWER (dBm)
14
4401 G05
1
–26 –20
–14 –8
–2
4
10
RF INPUT POWER (dBm)
16
4401 G06
U
U
U
SHDN (Pins 4/6):
Shutdown Input. A logic low on the SHDN
pin places the part in shutdown mode. A logic high places
the part in enable mode. SHDN has an internal 150k pull-
down resistor to ensure that the part is in shutdown when
the drivers are in a three-state condition.
V
PCA
(Pins 5/2):
Power Control Voltage Output. This pin
drives an external RF power amplifier power control pin.
The maximum load capacitance is 100pF.
V
CC
(Pins 6/1):
Input Supply Voltage, 2.7V to 6V. V
CC
should be bypassed with 0.1µF and 100pF ceramic capaci-
tors. Used as return for RF 250Ω termination.
BSEL (Pin 7): (LTC4401-2 Only)
Selects V
PCA
when Low
and V
PCB
when High. This input has an internal 150k
resistor to ground.
4401fa
LTC4401-1/LTC4401-2
BLOCK DIAGRA
68Ω
33pF
V
CC
6
250Ω
RF
1
28pF
30k
60µA
GND
2
60µA
VBG
V
REF
W
30k
(LTC4401-1)
RF IN
RF PA
50Ω
Li-Ion
TXENB
AUTOZERO
–
AZ
+
+
GAIN
COMPRESSION
–
GM
+
+
–
80mV
270kHz
FILTER
CLAMP
+
C
C
BUFFER
5
+
RF DET
38k
–
30k
30k
V
PCA
–
22k
51k
V
REF
+
–
33.4k
6k
12Ω
TXENB
10µs
DELAY
150k
LTC4401-1
4
SHDN
3
4401-1 BD
CONTROL
100Ω
PCTL
4401fa
5
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