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Preliminary
Product Description
Ordering Information
Typical Applications
Features
Functional Block Diagram
RF Micro Devices, Inc.
7625 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
1
2
3
4
8
7
6
5
BIAS
GND
IN
GND1
SELECT
OUT
VCC
GND2
Control Logic
RF2368
DCS/PCS 2.7V LOW NOISE AMPLIFIER
DCS Handsets
PCS Handsets
General Purpose Amplification
Commercial and Consumer Systems
The RF2368 is a DCS/PCS low noise amplifier with
bypass switch designed for use as a front-end for
DCS1800/PCS1900 applications. The LNA is a two-stage
amplifier with bypass switch. This amplifier has low noise
figure and high linearity in both high gain and bypass/low
gain mode.
Low Noise and High Intercept Point
Power Down Control
Switchable Gain
RF2368
DCS/PCS 2.7V Low Noise Amplifier
RF2368 PCBA
Fully Assembled Evaluation Board
4
Rev A0 010503
0.127
3MAX
0MIN
0.55
0.35
0.365
1.59
1.61
3.00
2.60
3.00
2.80
0.650
0.15
0.05
1.44
1.04
TEX
T
*
*When Pin 1 is in upper
left, text reads downward
(as shown).
Package Style: SOT 8 Lead
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Absolute Maximum Ratings
Parameter
Rating
Unit
Supply Voltage
-0.5 to +6.0
V
DC
Input RF Level
+10
dBm
Storage Temperature
-40 to +150
C
Parameter
Specification
Unit
Condition
Min.
Typ.
Max.
Operating Range
Overall Frequency Range
1800
2000
MHz
Supply Voltage (V
CC
)
2.7
2.78
2.86
V
V
CC1
, V
CC2
Power Down Voltage (V
BIAS
)
2.7
2.78
2.86
V
BIAS
Logic Control Voltage Level
0
2.86
V
SELECT
Operating Ambient Temperature
-40
+85
C
Input Impedance
50
Output Impedance
50
1850 MHz Performance
High Gain Mode
T = 25C, RF = 1850MHz, V
CC
= BIAS =2.78V,
SELECT = 0V, Z
IN
=Z
O
=50
Gain
17
18
19
dB
Gain Variation Over
Temperature Range
+0.5
dB
Gain Variation Over
Frequency Band
+0.5
dB
Current Consumption
9.0
9.5
mA
I
CC
+ I
BIAS
Noise Figure
1.6
1.7
dB
Reverse Isolation
15
20
dB
Input IP3
0.0
+1.0
dBm
Input P1dB
-13
-10
dB
1850 MHz Performance
Bypass Mode
T = 25C, RF = 1850MHz, VCC =2.78V,
SELECT = 2.7V, Z
IN
=Z
O
= 50
Gain
-4.5
dB
Gain Reduction
21
22.5
24
dBc
Power Down Current
10
A
Input IP3
12
15.0
dBm
Input P1dB
+5
+8
dB
1960 MHz Performance -
High Gain Mode
T = 25C, RF = 1960MHz, V
CC
= BIAS =2.78V,
SELECT = 0V, Z
IN
=Z
O
=50
Gain
15.5
16.5
17.5
dB
Gain Variation Over
Temperature Range
+0.5
dB
Gain Variation Over
Frequency Band
+0.5
dB
Current Consumption
9.0
9.5
mA
I
CC
+ I
BIAS
Noise Figure
1.6
1.7
dB
Reverse Isolation
15
20
dB
Input IP3
+1
+2
dBm
Input P1dB
-13
-10
dB
1960 MHz Performance -
Bypass Mode
T = 25C, RF = 1960MHz, VCC =2.78V,
SELECT = 2.7V, Z
IN
=Z
O
= 50
Gain
-5
dB
Gain Reduction
20
21.5
23
dBc
Power Down Current
10
A
Input IP3
14.0
17.0
dBm
Input P1dB
+5
+8
dB
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).
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Pin
Function
Description
Interface Schematic
1
BIAS
BIAS is set to the supply voltage at high gain mode. For bypass mode
see "Application Notes".
2
GND
3
IN
DCS1800/PCS1900 RF input pin.
4
GND1
LNA1 emittance inductance. Total inductance is comprised of
package+bondwire+L2 on PCB.
5
VCC
Open collector for first stage LNA of DCS1800/PCS1900. It must be
biased to V
CC
through a choke or matching inductor.
6
GND2
LNA2 emittance inductance. Total inductance is comprised of
package+bondwire+L4 on PCB.
7
OUT
DCS1800 Amplifier Output pin. This pin is an open-collector output. It
must be biased to V
CC
through a choke or matching inductor. This pin
is typically matched to 50
with a shunt bias/matching inductor and
series blocking/matching capacitor. Refer to application schematics.
8
SELECT
This pin selects high gain.
Select < 0.8V, high gain.
Select > 1.8V, low gain.
BIAS
RF IN
VCC1
To Bias
Circuit
GND1
VCC1
GND1
RF OUT
GND2
SELECT
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Application Notes
Bypass Mode Configurations
The RF2368 may be placed into either high gain or bypass mode via the GAIN SELECT pin (pin 8). The high gain state
is selected by asserting the GAIN SELECT pin to a voltage level of less than 0.8V. For Bypass operation, there are two
possible methods for placing the RF2368 into this low gain state. The table below shows the two possible Bypass config-
urations.
Bypass Mode Possibilities
For both Bypass configurations, the GAIN SELECT pin must be placed at a level greater than or equal to 1.8 V. The dif-
ference between the Bypass possibilities is determined by the specific application's ability to change the voltage of the
BIAS pin (pin 1) independently of the V
CC
supply voltage. The advantage of the ability to assert the power down pin to
0V when in Bypass mode is shown by the decreased current draw when in this Bypass configuration.
BIAS Pin Resistor
The BIAS pin (pin1) of the RF2368 should be maintained at 2.7V to 2.86V for proper high gain operation. This voltage
range ensures the correct bias current will be present at the BIAS pin of the device. However, an external series resistor
may be used to allow various operating voltages at this pin (see R1 of the evaluation board schematic). The required
value for this resistor may be roughly calculated by using the operating input voltage to the BIAS pin, the desired voltage
at the device, and the typical current consumption for the BIAS pin, along with Ohm's law.
For example, assume the design will supply 5.0V to the BIAS pin of the device, but the biasing circuitry internal to the
RF2368 requires 2.78V typical, and the BIAS current is known to typically be 0.25mA, then the required value for R1
would be found as follows.
Gain Select
BIAS (V)
VCC1 and VCC2 (V)
Current (mA)
2.7
0
2.78
1.4
2.7
2.7
2.78
2.2
5.0V
2.78V
0.25mA
--------------------------------
8.88k
=
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Application Schematic
2.7 nH
33 nF
8.2 nH
RFIN
0.1 uF
0
BIAS
0.1
F
SELECT
3.9 nH
10 k
10 nF
100 pF
VCC2
0.8 pF
RF OUT
1.5 nH
3.9 nH
10 k
10 nF
100 pF
VCC1
1
2
3
4
8
7
6
5
Control Logic
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Evaluation Board Schematic - PCS/DCS
(Download Bill of Materials from www.rfmd.com.)
L2
2.7 nH
C2
33 nF
L1
8.2 nH
C1
0.1 uF
R1
0
BIAS
C8
0.1
F
SELECT
L5
3.9 nH
R3
10 k
C6
100 pF
C7
10 nF
VCC2
C5
0.8 pF
L4
1.5 nH
L3
3.9 nH
R2
10 k
C3
10 nF
C4
100 pF
VCC1
1
2
3
4
8
7
6
5
Control Logic
P1
1
2
3
HDR_3
P1-1
BIAS
P1-3
SELECT
GND
P2-3
VCC1
P2-1
VCC2
GND
P2
1
2
3
HDR_3
50
strip
J2
RF OUT
50
strip
J1
RF IN
2368310, rev. 2
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Evaluation Board Layout
Board Size 1" x 1"
Board Thickness 0.032", Board Material FR-4
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S-Parameter Conditions:
All plots shown were taken at VCC =2.78V and Ambient Temperature=25C.
Note:
All S11 and S22 plots shown were taken from an RF2368 while on a 2368310 evaluation board. The data was captured without the exter-
nal input or output tuning components in place, and the reference points at the RF IN and RF OUT pins of the device.
0
1.
0
1.
0
-1
.
0
10.
0
10.0
-1
0.0
5.
0
5.0
-5
.0
2.
0
2.
0
-2
.0
3.
0
3.
0
-3
.0
4.
0
4.0
-4
.0
0.
2
0.2
-0.2
0.
4
0.
4
-0
.4
0.
6
0
.6
-0
.6
0.
8
0
.8
-0
.8
High Gain Mode Output Impedance (S22)
Swp Max
4GHz
Swp Min
0.01GHz
100 MHz
1.0 GHz
2.0 GHz
0
1.0
1.0
-1.0
10.0
10.0
-1
0.
0
5.0
5.
0
-5
.0
2.0
2
.
0
-
2
.
0
3.0
3.
0
-3
.0
4.0
4.
0
-4
.0
0.2
0.
2
-0
.2
0.4
0
.
4
-
0
.
4
0.6
0
.
6
-
0
.
6
0.8
0
.
8
-
0
.
8
High Gain Mode Input Impedance (S11)
Swp Max
4GHz
Swp Min
0.01GHz
3.0 GHz
1.0 GHz
1.5 GHz
2.0 GHz
0
1.
0
1.
0
-1
.
0
10.
0
10.0
-1
0.0
5.
0
5.0
-5
.0
2.
0
2.
0
-2
.0
3.
0
3.
0
-3
.0
4.
0
4.0
-4
.0
0.
2
0.2
-0.2
0.
4
0.
4
-0
.4
0.
6
0
.6
-0
.6
0.
8
0
.8
-0
.8
Bypass Mode Input Impedance (S11)
Swp Max
4GHz
Swp Min
0.01GHz
3.5 GHz
1.5 GHz
3.0 GHz
2.5 GHz
1.0 GHz
2.0 GHz
0
1.
0
1.
0
-1
.
0
10.
0
10.0
-1
0.0
5.
0
5.0
-5
.0
2.
0
2.
0
-2
.0
3.
0
3.
0
-3
.0
4.
0
4.0
-4
.0
0.
2
0.2
-0.2
0.
4
0.
4
-0
.4
0.
6
0
.6
-0
.6
0.
8
0
.8
-0
.8
Bypass Mode Output Impedance (S22)
Swp Max
4GHz
Swp Min
0.01GHz
3.0 GHz
3.7 GHz
1.0 GHz
2.0 GHz
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