Dual-Band, Image-Reject Downconverters For GSM Applications
The RF210A and RF210B devices are available as a dual-band front end for Global
System for Mobile Communications (GSM) handset applications. Both of these
highly integrated, monolithic devices are optimized for dual-band use in
GSM900/DCS1800 or GSM 900/PCS1900 applications. The devices include two
Low Noise Amplifiers (LNAs), two image-reject mixers, and two Local Oscillator
(LO) buffer amplifiers.
The main advantage of the RF210A and RF210B is their ability to provide 30 dB of
image rejection for both the GSM900 and the DCS1800 (or PCS1900) bands
without requiring the use of a post-LNA image reject filter. A block diagram of the
RF210(A/B) is shown in Figure 1. The device package and pin configuration are
shown in Figure 2.
LNA900GND
BIASGND
LNA900IN
0
90
90
IFOUT
Features
• LNA/image-reject mixer for RF to IF conversion
• 10 dB (RF210A) or 20 dB (RF210B) switchable
gain for GSM
• 8 dB (RF210A) or 16 dB (RF210B) switchable gain
for DCS/PCS
• 30 dB of image rejection. No post-LNA filtering
required
• High isolation LO input buffer
• Differential IF output
• High dynamic range
• Three-cell battery operation (2.7 to 5 V)
• 20-pin Thin Shrink Small Outline Package
(TSSOP)
Applications
• Dual-band digital cellular mobile telephony
(GSM900/DCS 1800 or GSM900/PCS1900)
NC
1
2
3
20
19
18
MIXVCC
MIXGND
BYP900
GAINSEL
LNA1800IN
BANDSEL
Data Sheet
IRM
0
90
BIAS
BYP900
BYP1800
Figure 1. RF210(A/B) Block Diagram
Proprietary Information and Specifications are Subject to ChangeOctober 20, 1999
The RF210(A/B) dual-band, image-reject downconverters
implement the front-end functions of a dual-band superheterodyne receiver. These devices consist of two receive
paths, one for GSM900 and the other for DCS1800 (or
PCS1900). Each receive path contains an LNA and an imagereject mixer. The IF and LO ports are common to both receive
paths. The image-reject mixers can provide 30 dB of image
rejection for both the GSM900 and the DCS1800 (or PCS1900)
bands without using any post-LNA image reject filters.
The LNA/mixer combination has a switchable gain. The RF210A
and RF210B both have 22 dB of gain in the high gain mode. For
the RF210A, the gain is reduced by 10 dB (GSM band) and by
8 dB (DCS/PCS band) in the low gain mode. For the RF210B,
the gain is reduced by 20 dB (GSM band) and by 16 dB
(DCS/PCS band) in the low gain mode. The gain mode is
selected using the GAINSEL pin (Pin 7). Low gain mode is
selected by driving the GAINSEL signal high; high gain mode is
selected by driving the signal low. In addition, small adjustments
Table 1. RF210(A/B) Signal Description
of the mixer gain can be accomplished by varying the quiescent
current on the ADJMIX pin (Pin 11). This pin can be connected
to VCC or ground through resistors. The current will increase if
the pin is connected to GND and decrease if connected to VCC.
For optimal performance, this pin should be left unconnected.
The band of operation for RF210(A/B) is selected by the
BANDSEL signal on Pin 14. It switches the receive path
between GSM900 and DCS1800 (or PCS1900) bands.
The device can operate from a three-cell battery pack (2.7 V to
5.0 V). Standby mode current is extremely low at 20 µA, which
maximizes handset standby time.
The signal pin assignments and functional pin descriptions are
found in Table 1. The absolute maximum ratings of the
RF210(A/B) are provided in Table 2, the operating conditions
are specified in Table 3, and electrical specifications are
provided in Table 4. Figure 3 shows the diagram for a typical
application circuit using the RF210(A/B) downconverter. Figure
4 provides the package dimensions for the 20-pin TSSOP
device and Figure 5 provides the tape and reel dimensions.
Table 4. RF210(A/B) Electrical Specifications (1 of 2)
A
(T
= 25 C, Vcc = 3.0 V,
IF
f
= 400 MHz,
Plo
= –10 dBm)
ParameterTest ConditionMinTypicalMaxUnits
GSM900 Mode, BANDSEL = 0
Supply current:
Enable mode
Sleep mode
RF Input frequency935960MHz
IF frequency350400450MHz
LO frequency12851410MHz
LO input power–10dBm
LO to RF input isolation30dB
Input impedanceLNA900IN = 950 MHz40 – j50
Gain:
High gain (RF210A and RF210B)
Low gain (10 dB attenuation, RF210A)
Low gain (20 dB attenuation, RF210B)
Gain variation vs. Frequency
Gain step tracking error
Noise figure:
High gain
Low gain (12 dB gain, RF210A)
Low gain (2 dB gain, RF210B)
High gain (Note 1)
Input 1 dB compression point–25dBm
Input third order i ntercept point–17dBm
IF shunt resis tance/side400500600
Spurious response:
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