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
LOIN
LNA900IN
IFout
LNA900IN
IFout
LNA1800IN
LNA1800IN
LNA1900IN
Band Select 1
control
Band Select 1
Band Select 2
control
Step
Sel
Gain
Sel
C0002
Step
Sel
Gain
Sel
C0001
Figure 1. RF212 Dual-Band Device Block Diagram
Figure 2. RF212 Tri-Band Device Block Diagram
Data Sheet
Conexant
Proprietary Information and Specifications are Subject to Change
Doc. No. 100780D
May 24, 2000
RF212
Image-Reject Front End
NC
GND
GND
LNA900IN
VCC
VCC
GAINSEL
LNA1800IN
GND
ENA
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
VCC
GND
STEPSEL
IFOUT+
IFOUT-
GND
BANDSEL1
LOIN
LOGND
NC
C067
NC
GND
GND
LNA900IN
VCC
VCC
GAINSEL
LNA1800IN
LNA1900IN
ENA
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
VCC
GND
STEPSEL
IFOUT+
IFOUT-
BANDSEL2
BANDSEL1
LOIN
LOGND
NC
C122
Figure 3. RF212 Dual-Band Device Pin Configuration
−
20-Pin
ETSSOP
Figure 4. RF212 Tri-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 image-
reject filter, and a mixer. The IF and LO ports are common to all
frequency bands. The image rejection achievable by this front-
end 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.
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 (tri-
band). 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
Conexant
Proprietary Information and Specifications are Subject to Change
100780D
Image-Reject Front End
RF212
Table 1. RF212 Dual-Band Selection
BANDSEL1, pin 14
0
1
Mode
EGSM900
DCS1800
Table 2. RF212 Tri-Band Selection
BANDSEL1, pin 14
0
0
1
1
BANDSEL2, pin 15
0
1
0
1
Mode
EGSM900
DCS1800
PCS1900
Table 3. RF212 Dual-Band Device Signal Description
Pin #
1
2
3
4
5
6
7
8
NC
GND
GND
LNA900IN
VCC
VCC
GAINSEL
LNA1800IN
Name
Description
No connect (recommend connecting to
ground)
Ground
Ground
900 MHz LNA input
Supply
Supply
LNA gain select
1800 MHz LNA input
Pin #
11
12
13
14
15
16
17
18
NC
Name
Description
No connect (recommend connecting to
ground)
LO input ground
LO input
Band select control
Ground
Mixer negative output
Mixer positive output
Gain step select. STEPSEL= 0 selects a
12 dB gain step; STEPSEL = 1 selects a
20 dB gain step
Ground
Supply
LOGND
LOIN
BANDSEL1
GND
IFOUT−
IFOUT+
STEPSEL
9
10
GND
ENA
Ground
Device enable, active high
19
20
GND
VCC
Table 4. RF212 Tri-Band Device Signal Description
Pin #
1
2
3
4
5
6
7
8
NC
GND
GND
LNA900IN
VCC
VCC
GAINSEL
LNA1800IN
Name
Description
No connect (recommend connecting to
ground)
Ground
Ground
900 MHz LNA input
Supply
Supply
LNA gain select
1800 MHz LNA input
Pin #
11
12
13
14
15
16
17
18
NC
Name
Description
No connect (recommend connecting to
ground)
LO input ground
LO input
Band select control 1
Band select control 2
Mixer negative output
Mixer positive output
Gain step select. STEPSEL= 0 selects a
12 dB gain step; STEPSEL = 1 selects a
20 dB gain step
Ground
Supply
LOGND
LOIN
BANDSEL1
BANDSEL2
IFOUT−
IFOUT+
STEPSEL
9
10
LNA1900IN
ENA
1900 MHz LNA input
Device enable, active high
19
20
GND
VCC
100956A
May 18, 2000
Conexant – Preliminary
Proprietary Information and Specifications are Subject to Change
3
RF212
Image-Reject Front End
Table 5. Absolute Maximum Ratings
Parameter
Storage Temperature
Supply Voltage (VCC)
Input Voltage Range
Minimum
−40
−0.3
−0.3
Maximum
+125
+3.6
Vcc
Units
°C
V
V
Table 6. RF212 Recommended Operating Conditions
Parameter
Supply Voltage
Operating Temperature
Min
2.7
−30
Typical
3.0
+25
Max
3.6
+85
Units
V
°C
(T
A
= 25
°
C, Vcc = 2.7 V,
f
IF
= 400 MHz,
Plo
=
−
10 dBm)
Table 7. RF212 Electrical Specifications (1 of 3)
Symbol
Test Condition
EGSM900 Mode
Parameter
Supply current::
Enable mode
Sleep mode
RF Input frequency
IF frequency
LO to RF input isolation
Input impedance
Power gain (for 2 kΩ differential output impedance):
High gain mode
Low gain mode 1
Low gain mode 2
Gain step 1
Gain step 2
Temperature coefficient
Gain variation versus frequency
Noise figure:
High gain
Low gain mode 1
Low gain mode 2
Noise figure degradation with blocker:
High gain
Input 1 dB compression point
Input third order intercept point
Differential IF shunt output resistance
Image rejection:
f
IF
= 400 MHz
f
IF
= 350 or 450 MHz
Min
Typical
Max
Units
ENA = 1
ENA = 0
925
f
IF
350
30
15
30
960
400
50
450
mA
µA
MHz
MHz
dB
Ω
G
MAX
1
G
MIN
1
G
MIN
2
G
STEP
1
G
STEP
2
F
TC
1
GAINSEL = 0
GAINSEL = 1, STEPSEL = 1
GAINSEL = 1, STEPSEL = 0
20
–24
–14
22
0
10
–22
–12
–0.02
25
–20
–10
0.8
dB
dB
dB
dB
dB
dB/°C
dB
dB
dB
dB
dB
dBm
dBm
dBm
kΩ
dB
dB
GAINSEL = 0
GAINSEL = 1, STEPSEL = 1
GAINSEL = 1, STEPSEL = 0
−22
dBm blocker,
GAINSEL = 0 (Note 1)
IP
1
D
B
IP3
high gain mode
low gain mode
−22
−18
2.3
18
10
1.6
–20
–13
−12
2
35
25
50
3.5
4
May 24, 2000
Conexant
Proprietary Information and Specifications are Subject to Change
100780D
Image-Reject Front End
RF212
(T
A
= 25
°
C, Vcc = 2.7 V,
f
IF
= 400 MHz,
Plo
=
−
10 dBm)
Table 7. RF212 Electrical Specifications (2 of 3)
Symbol
Test Condition
DCS1800 Mode
Parameter
Supply current:
Enable mode
Sleep mode
RF input frequency
IF frequency
LO to RF input isolation
Input impedance
Power gain (for 2 kΩ differential output impedance):
High gain mode
Low gain mode 1
Low gain mode 2
Gain step 1
Gain step 2
Temperature coefficient
Gain variation versus frequency
Noise figure:
High gain
Low gain mode 1
Low gain mode 2
Noise figure degradation with blocker:
High gain
Input 1 dB compression point
Input third order intercept point
Differential IF shunt output resistance
Image rejection:
f
IF
= 400 MHz
f
IF
= 350 or 450 MHz
Min
Typical
Max
Units
ENA = 1
ENA = 0
1805
350
30
19
30
1880
400
50
450
mA
µA
MHz
MHz
dB
Ω
G
MAX
1
G
MIN
1
G
MIN
2
G
STEP
1
G
STEP
2
F
TC
1
GAINSEL = 0
GAINSEL = 1, STEPSEL = 1
GAINSEL = 1, STEPSEL = 0
20
–22
–14
22
2
10
–20
–12
–0.02
25
–18
–10
1.2
dB
dB
dB
dB
dB
dB/°C
dB
dB
dB
dB
dB
dBm
dBm
dBm
kΩ
dB
dB
GAINSEL = 0
GAINSEL = 1, STEPSEL = 1
GAINSEL = 1, STEPSEL = 0
−22
dBm blocker,
GAINSEL = 0 (Note 2)
IP
1
D
B
IP3
high gain mode
low gain mode
−23
−20
3.5
16.5
11
1.6
–20
–16
−12
2
35
25
40
4.5
PCS1900 Mode (for tri-band device only)
Supply current:
Enable mode
Sleep mode
RF input frequency
IF frequency
LO to RF input isolation
Input impedance
Power gain (for 2 kΩ differential output impedance):
High gain mode
Low gain mode 1
Low gain mode 2
Gain step 1
Gain step 2
Temperature coefficient
Gain variation versus frequency
Noise figure:
High gain
Low gain mode 1
Low gain mode 2
Noise figure degradation with blocker:
High gain
G
MAX
1
G
MIN
1
G
MIN
2
G
STEP
1
G
STEP
2
F
TC
1
GAINSEL = 0
GAINSEL = 1, STEPSEL = 1
GAINSEL = 1, STEPSEL = 0
20
–22
–14
ENA = 1
ENA = 0
1930
350
30
50
22
2
10
–20
–12
–0.02
25
–18
–10
1.2
GAINSEL = 0
GAINSEL = 1, STEPSEL = 1
GAINSEL = 1, STEPSEL = 0
−22
dBm blocker,
GAINSEL = 0 (Note 3)
3.5
16.5
11
1.6
4.5
400
19
30
1990
450
mA
µA
MHz
MHz
dB
Ω
dB
dB
dB
dB
dB
dB/°C
dB
dB
dB
dB
dB
100956A
May 18, 2000
Conexant – Preliminary
Proprietary Information and Specifications are Subject to Change
5
