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PDF RF2494 Data sheet ( Hoja de datos )
| Número de pieza | RF2494 | |
| Descripción | HIGH FREQUENCY LNA/MIXER | |
| Fabricantes | RF Micro Devices | |
| Logotipo |  |
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Preliminary
8
RF2494
HIGH FREQUENCY LNA/MIXER
Typical Applications
• Part of 2.4GHz IEEE802.11b WLANs
• WLAN or Wireless Local Loop
• Digital Communication Systems
• Portable Battery-Powered Equipment
• Spread-Spectrum Communication Systems • UHF Digital and Analog Receivers
Product Description
The RF2494 is a monolithic integrated UHF receiver front
end suitable for 2.4GHz ISM band applications. The IC
contains all of the required components to implement the
RF functions of the receiver except for the passive filter-
ing and LO generation. It contains an LNA (low-noise
amplifier), a second RF amplifier and a doubly balanced
mixer. The output of the LNA is made available as an out-
put to permit the insertion of a bandpass filter between
the LNA and the RF/Mixer section. The mixer outputs can
be selectively disabled to allow for the IF filter to be used
in the transmit mode.
Optimum Technology Matching® Applied
Si BJT
üSi Bi-CMOS
GaAs HBT
SiGe HBT
GaAs MESFET
Si CMOS
16 15 14
PD 1
Bias
VCC1 2 Circuits
LNA
13
12 NC
11 NC
VCC2 3
RF AMP 10 MIX IN
MIX OUT- 4
9 GND3
5678
1.00
.80 0.85
.65
.60
.24 typ
2
.35
.23
4.00
sq.
.65
.30
4 PLCS
1.85
1.55 sq.
12°
max
.05
.01
NOTES:
.75
.50
.23
.13
.65 4 PLCS
Dimensions in mm.
1 Shaded Pin is Lead 1.
2
Dimension applies to plated terminal and is measured between 0.02 mm and
0.25 mm from terminal end.
3 Pin 1 identifier must exist on top surface of package by identification mark or
feature on the package body. Exact shape and size is optional.
4 Package Warpage: 0.05 max.
5 Die thickness allowable: 0.305 mm max.
Package Style: LCC, 16-Pin, 4x4
Features
• Single 2.7V to 3.6V Power Supply
• 2400MHz to 2500MHz Operation
• Two Gain Settings: 28dB or 12dB
• 4.5dB Cascaded NF, High Gain Mode
• 20mA DC Current Consumption
• Input IP3: -23dBm or -8dBm
Ordering Information
RF2494
High Frequency LNA/Mixer
RF2494 PCBA-H Fully Assembled Evaluation Board (2.5GHz)
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
8
Rev A0 010730
8-53
1 page  
Preliminary
RF2494
Theory of Operation
RF Micro Devices
2.4 GHz ISM Chipset
IL = 1-3 dB
2.4 to 2.483 GHz
Gain
Select
RF2494
SSOP-16 EPP
Filter
2.4 to 2.483 GHz
LNA
Dual Gain Modes
-5 dB and +10 dB
15 dB Gain
RX
SAW
IL = 10 dB max
T/R
Switch
Dual
Frequency
Synthesizer
RF
VCO
IF
VCO
RX
15 dB
IF Amp
-15 dB to 35 dB Gain
TX
15 dB
TX
+45
*2 °
-45°
RF2189
Figure 1. Entire Chipset Functional Block Diagram
10 dBm
PA Driver
IL = 1-3 dB
2.4 to 2.483 GHz
15 dB Gain
Range
Σ
TX VGC
RX VGC
RF2948
OUT Q
Base Band Amp.
Active Selectable LPF
(fC = 1 MHz to 40 MHz)
0-30 dB Gain
OUT I
Filter
I INPUT
Filter
Selectable LPF
Q INPUT
The RF2494 contains the LNA/Mixer for this chipset.
The LNA is made from two stages including a common
emitter amplifier stage with a power gain of 13dB and
an attenuator which has an insertion loss of 3dB in
high gain mode, and 17dB in low gain mode. The
attenuator was put after the LNA so that system noise
figure degradation would be minimized. A single gain
stage was used prior to the image filter to maximize
IP3 which minimizes the risk of large out-of-bad signals
jamming the desired signal.
The mixer on the RF2494 is also two stages. The first
stage is a common emitter amp used to boost the total
power gain prior to the lossy SAW filter, to convert to a
differential signal to the input of the mixer, and to
improve the noise figure of the mixer. The second
stage is a double balanced mixer whose output is dif-
ferential open collector. It is recommended that a “cur-
rent combiner” is used (as shown in figure 2) at the
mixer output to maximize conversion gain, but other
loads can also be used. The current combiner is used
to do a differential to single ended conversion for the
SAW filter. C1, C2 and L1 are used to tune the circuit
for a specific IF frequency. L2 is a choke to supply DC
current to the mixer that is also used as a tuning ele-
ment, along with C3, to match to the SAW filter’s input
impedance. RL is the SAW filter’s input impedance.
The mixer power conversion gain is +19dB when R1 is
set to 1k Ω. The conversion gain can be adjusted up
~5dB or down ~7dB by changing the value of R1.
Once R1 is chosen, L2 and C3 can be used to tune the
output for the SAW filter.
VCC
C1 C2 L2
L1
R1
Open Collector
Mixer Output
C3
OUT
RL
8
Figure 2. Current Combiner for Mixer Load
The cascaded power gain of the LNA/Mixer is 29dB,
which after insertion loss in the image filter (~3dB) and
IF SAW filter (~10dB), still gives 16dB of gain prior to
the IF amps. Because of this, the noise figure of the IF
amps should not significantly degrade system noise
figure.
The LNA input should be matched for a good return
loss for optimum gain and noise figure. To allow the
designer to match each of these ports, 2-port s-param-
eter data is available for the LNA, and 1-port data is
available for MIXER IN and LO IN.
Rev A0 010730
8-57
5 Page 
Preliminary
10.5
10.4
10.3
10.2
10.1
10.0
9.9
9.8
9.7
9.6
9.5
2.7
-4.0
-4.2
-4.4
LNA Gain versus VCC (2.45 GHz),
Attenuator Off
-40C Gain
25C Gain
85C Gain
3.0 3.3
VCC
LNA Gain versus VCC (2.45 GHz),
Attenuator On
-40C Gain
25C Gain
85C Gain
-4.6
-4.8
-5.0
-5.2
-5.4
-5.6
2.7
10.70
10.60
10.50
10.40
10.30
10.20
10.10
10.00
9.90
9.80
9.70
2.40
3.0 3.3
VCC
LNA Gain versus RF Frequency (3.3 V),
Attenuator Off
-40C Gain
25C Gain
85C Gain
2.45
RF Frequency (GHz)
Rev A0 010730
3.6
3.6
2.50
RF2494
-2.0
-2.1
-2.2
-2.3
-2.4
-2.5
-2.6
-2.7
-2.8
2.7
-1.8
LNA IIP3 versus VCC (2.45 GHz),
Attenuator Off
-40C IIP3
25C IIP3
85C IIP3
3.0 3.3
VCC
LNA IIP3 versus VCC (2.45 GHz),
Attenuator On
3.6
-2.0
8
-2.2
-40C IIP3
-2.4 25C IIP3
85C IIP3
-2.6
-2.8
-3.0
2.7
0.00
-0.50
-1.00
3.0 3.3
VCC
3.6
LNA IIP3 versus RF Frequency (3.3 V),
Attenuator Off
-40C IIP3
25C IIP3
85C IIP3
-1.50
-2.00
-2.50
-3.00
-3.50
2.40
2.45
RF Frequency (GHz)
2.50
8-63
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet RF2494.PDF ] | |
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