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Copyright 1997-2000 RF Micro Devices, Inc.
A front end RFIC for cordless telephone applications
has been developed for use in the 902MHz to 928 MHz
ISM (Industrial-Scientific-Medical) band in the United
States under Part 15 of the FCC Rules. Potential appli-
cations for this RFIC in this frequency band include
cordless telephones, wireless LANs, wireless security
systems and point-of-sale (POS) terminals.
This RFIC, the RF2403, consists of a single-stage
LNA, a two-stage PA with 21dBm of output power and
a transmit/receive switch. The RFIC is built using a
commercial GaAs MESFET process, and is packaged
in a SOP-16 narrowbody surface-mount package. The
circuit operates with a +5.0V supply, and has separate
enable lines which control the bias to the transmit and
receive functions. All bias and control signals operate
with voltages which lie between ground potential and
VDD. With both enable lines at logic low, the circuit is in
a “power down” mode in which it draws approximately
1.0mA of leakage current from the VDD supply. Some
external passive components are required, primarily for
DC blocking and RF bypassing functions. The PA out-
put impedance matching circuitry, consisting of a pi-
network, is realized using external passive compo-
nents in order to both conserve die area and to reduce
parasitic losses. This same RFIC has been evaluated
for use in 433MHz European applications, and has
been found to have very good RF performance there.
Although no changes have been made to the RFIC
itself, several changes to the application circuit are
necessary for operation at 433MHz. Table 1 shows the
component values for both versions of the RF2403
application circuit. The two application schematics are
shown, for 433MHz operation and for 915 MHz opera-
tion, in Figures 1 and 2, respectively. The resulting RF
performance for these circuits is shown in Table 2. The
I/O port return losses are somewhat degraded at
433MHz, primarily due to the excess reactance of the
on-chip DC blocking capacitors in the RFIC. The
RF2403 does have comparable gain, output power and
linearity at 433MHz with respect to its performance at
915MHz.
RF Specification
Measured Performance (All Typical) @V
DD =5.0 V
433MHz Circuit
915MHz Circuit
LNA Gain1
17dB
16dB
LNA NF1
2.4dB
2.7dB
LNA P1dB
1
+6.0dBm
+6.0dBm
RX IRL, ANT port1
6.0dB
9.0dB
LNA ORL
15dB
13dB
PA Small Signal Gain1
28dB
28dB
PA P1dB
1
19.0dBm
21.0dBm
PA IRL
11dB
17dB
PA ORL, ANT port1
11.5dB
10.5dB
PA Two-tone POUT
1,2
@ -25dBc IMD3
17.5dBm
16.7dBm
Table 2. RF2403 measured performance, using the two application schematics
Note 1: Performance is measured through the monolithic T/R switch
Note 2: f1=432.5MHz, f2=433.5MHz, or, f1=914.5MHz, f2=915.5MHz
TA0016
TA0016
RF2403: European Applications for RF2403 Cordless Telephone Front
End RFIC
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