4-1
Product Description
Ordering Information
Typical Applications
Features
Functional Block Diagram
RF Micro Devices, Inc.
7628 Thorndike Road
Greensboro, NC 27409, USA
Tel (336) 664 1233
Fax (336) 664 0454
http://www.rfmd.com
Optimum Technology Matching Applied
Si BJT
GaAs MESFET
GaAs HBT
Si Bi-CMOS
!
SiGe HBT
Si CMOS
4
GENERAL PUR
P
OSE
AM
PLIFIERS
GaInP/HBT
GaN HEMT
SiGe Bi-CMOS
8
7
6
5
RF IN
GND1
GND2
IPSET
1
2
3
4
RF OUT
ISET
VCC
ENABLE
Bias Circuits
RF2451
3V LOW NOISE AMPLIFIER
GSM Handsets
CDMA Handsets
TDMA Handsets
IF or RF Buffer Amplifiers
Driver Stage for Power Amplifiers
Oscillator Loop Amplifiers
The RF2451 is a general purpose, low-cost, high perfor-
mance low noise amplifier designed for operation from a
2.7V to 4V supply with low current consumption. The
attenuation of the device is controlled when in power
down mode, providing a known gain step. The RF2451 is
available in a small industry-standard MSOP-8 surface
mount package, enabling compact designs which con-
serve board space. The design features accurate PTAT
(Proportional To Absolute Temperature) biasing scheme
using band gap cells.
700MHz to 2000MHz Operation
2.7V to 3.6V Single Supply
+5dBm Input IP
3
at 3.0mA
12dB Gain at 1950MHz
1.8dB Noise Figure at 1950MHz
17dB Gain Step
RF2451
3V Low Noise Amplifier
RF2451 PCBA
Fully Assembled Evaluation Board
4
Rev A9 020528
.026
.120
.116
10MAX
0MIN
.009
.005
.120
.116
.196
.190
1
.016
.010
.036
.032
.006
.002
.027
.017
Package Style: MSOP-8
4-2
RF2451
Rev A9 020528
4
GENERAL PUR
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AM
PLIFIERS
Absolute Maximum Ratings
Parameter
Rating
Unit
Supply Voltage
4.0
V
Supply Current
20
mA
Operating Ambient Temperature
-40 to +85
C
Storage Temperature
-40 to +150
C
Parameter
Specification
Unit
Condition
Min.
Typ.
Max.
Overall
T=27C, V
CC
=2.7V, V
IPSET
=0V,
V
ENABLE
=2.7V
Frequency Range
700 to 2000
MHz
LNA Performance
Freq=1.95GHz
Gain
10.5
12.5
dB
Noise Figure
1.6
dB
Input IP3
+4.5
+8
dBm
At 2.9mA
Input VSWR
5:1
dB
(Noise match)
Output VSWR
1.5:1
dB
Off Mode Gain
-5.0
dB
V
ENABLE
=0V
Gain
17
dB
Freq=836MHz
Noise Figure
1.6
dB
Input IP3
0
dBm
Off Mode Gain
-8
dB
V
ENABLE
=0V
Current Control
Internal current setting "ON"
CMOS Low
V
Voltage on IPSET
External current setting "ON"
CMOS High
V
Voltage on IPSET
Current into ISELECT
1
A
V
ISELECT
=2.7V
Power Control
Power "ON" Voltage
CMOS High
V
Voltage on ENABLE
Power "OFF" Voltage
CMOS Low
V
Voltage on ENABLE
Current into ENABLE
1
A
V
ENABLE
=2.7V
Power Supply
Operating Voltage
2.7 to 3.6
V
Operating Current
2.9
5
mA
V
CC
=2.7V, Internal current setting
Leakage Current
1
A
V
ENABLE
=0V
Caution! ESD sensitive device.
RF Micro Devices believes the furnished information is correct and accurate
at the time of this printing. However, RF Micro Devices reserves the right to
make changes to its products without notice. RF Micro Devices does not
assume responsibility for the use of the described product(s).
4-3
RF2451
Rev A9 020528
4
GENERAL PUR
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AM
PLIFIERS
Pin
Function
Description
Interface Schematic
1
RF OUT
RF output pin. Bias for the LNA is provided through this pin, hence it
should be connected to VCC through an inductor.
2
ISET
This pin sets the current for the device. A resistor to ground of 1k
pro-
vides a current of 17.5mA. The condition for optimal IP3 is to use the
internal current setting option and leave this pin open (no connect).
3
VCC
Power supply for the bias circuits.
4
ENABLE
Power down control. This is a CMOS input. When this pin is CMOS
"high" the device is enabled. When the level is CMOS "low" the device
is shut off and a controlled attenuator is turned on.
5
IPSET
This pin selects the internal current setting when CMOS level "low", and
the external current setting when this pin is CMOS level "high". The cur-
rent is set to 2.8mA using the internal current setting, and can be up to
20mA using the external current setting.
6
GND2
Ground connection for the bias circuits.
7
GND1
Ground connection for the LNA. Keep traces physically short and con-
nect immediately to ground plane for best performance.
8
RF IN
RF input pin. This pin is not internally DC blocked and requires an
external blocking capacitor.
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