Conexant RF212-11, RF212-21 Datasheet
RF212
Image-Reject Front End for Dual or Tri-Band GSM Applications
The RF212 device is available as a dual-band (EGSM900/DCS1800) front end or
as a tri-band (EGSM900/DCS1800/PCS1900) front end for Global System for
Mobile Communications (GSM) mobile telephony applications. Each device
integrates all the required front-end components after the frequency pre-select
filters. These components include the Low Noise Amplifiers (LNAs), the internal
image-reject filters, mixers, and a Local Oscillator (LO) amplifier.
The main advantage of the RF212 is its ability to provide a minimum of 35 dB of
image rejection for each band. The block diagrams of the devices are shown in
Figures 1 and 2. The device packages and pin configurations are shown in Figures
3 and 4.
Features
• Supports EGSM
• LNA and mixer for RF to IF conversion
• 12 dB or 20 dB switchable gain step
• Minimum 35 dB of image rejection
• No external post-LNA filters required
• Common Intermediate Frequency (IF) port for all
bands
• IF range from 350 MHz to 450 MHz
• High isolation LO input buffer
• Differential IF output
• High dynamic range with low current consumption
• Three-cell battery operation (2.7 to 3.6 V)
• 20-pin Exposed paddle, Thin Shrink Small Outline
Package (ETSSOP)
Applications
• Dual/tri-band digital cellular mobile telephony
(EGSM900/DCS1800, or
EGSM900/DCS1800/PCS1900)
LOIN
LNA900IN IFout
LNA1800IN
control
Gain
Step
Sel
Sel
Figure 1. RF212 Dual-Band Device Block Diagram
Data Sheet
Proprietary Information and Specifications are Subject to Change May 24, 2000
Band Select 1
C0002
Conexant
LOIN
LNA900IN IFout
LNA1800IN
LNA1900IN
Band Select 1
Band Select 2
Sel
Step
Sel
control
Gain
Figure 2. RF212 Tri-Band Device Block Diagram
Doc. No. 100780D
C0001
RF212 Image-Reject Front End
GND
GND
LNA900IN
VCC
VCC
GAINSEL
LNA1800IN
GND
ENA
NC
1
2
3
4
5
6
7
8
9
10
VCC
20
GND
19
STEPSEL
18
IFOUT+
17
IFOUT-
16
GND
15
BANDSEL1
14
LOIN
13
LOGND
12
NC
11
C067
Figure 3. RF212 Dual-Band Device Pin Configuration −−−− 20-Pin
ETSSOP
Technical Description
Both RF212 devices form front ends of a dual-band or a tri-band
super-heterodyne receiver. The RF212 dual-band device is
optimized for an EGSM900/DCS1800 design, while the RF212
tri-band device is suitable for EGSM900, DCS1800, and PCS
1900. Each frequency band has its own separate front-end
receiver path. Each receiver path contains an LNA, an imagereject filter, and a mixer. The IF and LO ports are common to all
frequency bands. The image rejection achievable by this frontend design without any additional external components is 35 dB
minimum for an IF of 400 MHz. Both devices operate over a
supply voltage range of 2.7 V to 3.6 V.
The RF212 dual-band device has one band selection pin
(BANDSEL1 on pin 14). When BANDSEL1 is set to logic “0,” the
EGSM900 receiver path is active. The LO frequency needs to
be higher than the RF input frequency (i.e., a high side injection
is used). When BANDSEL1 is set to logic “1,” the DCS1800
receiver path is active. The LO frequency needs to be less than
the RF input frequency (i.e., a low-side injection is used). With a
400 MHz IF, this arrangement allows a single, wide-range
Voltage Controlled Oscillator (VCO) to be used for each band of
operation.
GND
GND
LNA900IN
VCC
VCC
GAINSEL
LNA1800IN
LNA1900IN
ENA
NC
1
2
3
4
5
6
7
8
9
10
VCC
20
GND
19
STEPSEL
18
IFOUT+
17
IFOUT-
16
BANDSEL2
15
BANDSEL1
14
LOIN
13
LOGND
12
NC
11
C122
Figure 4. RF212 Tri-Band Device Pin Configuration – 20-Pin
ETSSOP
Similarly, the RF212 tri-band device has two band selection pins
(BANDSEL1 and BANDSEL2, pins 14 and 15, respectively). The
EGSM900 path uses the high side injection for the LO, while
DCS1800 and PCS1900 paths use the low side injection. Tables
1 and 2 provide the frequency band selection settings for the
dual and tri-band devices, respectively.
All the LNAs have switchable gain. The gain mode is selectable
using the GAINSEL signal (pin 7). Low gain mode is selected by
driving the GAINSEL signal to a logic “1”; high gain mode is
selected by driving the signal to a logic “0.” Depending on the
need of the handset design on the gain distribution, the gain
step between the high gain and low gain modes can be set to
either a 12 dB step or a 20 dB step. This gain step is selectable
with the STEPSEL signal (pin 18).
Electrical and Mechanical Specifications________________
The RF212 signal pin assignments and functional pin
descriptions are found in Table 3 (dual-band) and Table 4 (triband). The absolute maximum ratings of the RF212 are
provided in Table 5, the operating conditions are specified in
Table 6, and electrical specifications are provided in Table 7.
Figure 3 shows the diagram for a typical application circuit using
the RF212 front end. Figure 4 provides the package dimensions
for both of the 20-pin ETSSOP devices.
ESD Sensitivity
The RF212 is a static-sensitive electronic device. Do not operate
or store near strong electrostatic fields. Take proper ESD
precautions.
2
May 24, 2000 Proprietary Information and Specifications are Subject to Change
Conexant
100780D
Image-Reject Front End RF212
Table 1. RF212 Dual-Band Selection
BANDSEL1, pin 14 Mode
0 EGSM900
1 DCS1800
Table 2. RF212 Tri-Band Selection
BANDSEL1, pin 14 BANDSEL2, pin 15 Mode
0
0
1 0 DCS1800
1 1 PCS1900
0
1
EGSM900
Table 3. RF212 Dual-Band Device Signal Description
Pin # Name Description Pin # Name Description
1 NC No connect (recommend c onnecting to
ground)
2 GND Ground 12 LOGND LO input ground
3 GND Ground 13 LOIN LO input
4 LNA900IN 900 MHz LNA input 14 BANDSEL1 Band select control
5 VCC Supply 15 GND Ground
6 VCC Supply 16
7 GAINSEL LNA gain select 17 IFOUT+ Mixer posi tive output
8 LNA1800IN 1800 MHz LNA input 18 STEPSEL Gain step select. STEPSEL= 0 selects a
9 GND Ground 19 GND Ground
10 ENA Device enable, active high 20 VCC Supply
11 NC No connect (recommend c onnecting to
IFOUT−
ground)
Mixer negative output
12 dB gain step; STEPSEL = 1 selec ts a
20 dB gain step
Table 4. RF212 Tri-Band Device Signal Description
Pin # Name Description Pin # Name Description
1 NC No connect (recommend c onnecting to
2 GND Ground 12 LOGND LO input ground
3 GND Ground 13 LOIN LO input
4 LNA900IN 900 MHz LNA input 14 BANDSEL1 Band select control 1
5 VCC Supply 15 BANDSEL2 Band select control 2
6 VCC Supply 16
7 GAINSEL LNA gain select 17 IFOUT+ Mixer posi tive output
8 LNA1800IN 1800 MHz LNA input 18 STEPSEL Gain step select. STEPSEL= 0 selects a
9 LNA1900IN 1900 MHz LNA input 19 GND Ground
10 ENA Device enable, active high 20 VCC Supply
100956A
ground)
Conexant – Preliminary
11 NC No connect (recommend c onnecting to
IFOUT−
ground)
Mixer negative output
12 dB gain step; STEPSEL = 1 selec ts a
20 dB gain step
May 18, 2000 Proprietary Information and Specifications are Subject to Change
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