CHR2244 Datasheet, PDF (12/16 Pages) United Monolithic Semiconductors – 5.8 GHz One Antenna Reflective Transponder for Tag GaAs Monolithic Microwave IC

CHR2244
5.8 GHz One Antenna Reflective Tag
Tag operating modes
Within this transmission system, The CHR2244 operates in three basic modes depending on the WK_in
and T/R input signal levels. They are described hereafter :
1 - The STANDBY MODE (figure 2) is a very low power consumption state. In this mode an
Amplitude Modulated RF signal is necessary to produce a DC voltage at the SB_out output which may be
used to wake-up the CHR2244 by applying Vcc to the WK_in input.
Data from controller
T/R
MOD
0V or HI 0V or HI
WK_in
0V or HI
RF-in
AM
modulated
TR
0V
RF in
Det
AM
modulated
DATA_out
SB_out
to controller
WKIN
0V
SB_out
Vcc
Figure 2a : Standby mode
The received AM modulated RF spectrum is the following, versus the modulation index (m). This
plot is done for the minimum AM modulated RF input power ( -40 dBm ) and only for an ideal spectrum
with only 2 rows ( 5.7995 and 5.8005 GHz ) i.e. the 5.8 GHz carrier AM modulated with a 500 kHz signal.
-40dBm
5.8GHz
12dB
5.8GHz
9dB
5.8GHz
7dB
5.7995GHz
5.8005GHz
m=0.5
5.7995GHz
5.8005GHz
m=0.7
5.7995GHz
5.8005GHz
m=0.9
Figure 2b : AM modulated RF spectrum
IF 500kHz
ATTENUATOR
MODULATOR
SB_OUT
+V
CHR2244
OSCILLOSCOPE
RF
5,8GHz
Figure 2c : Standby test bench diagram
Ref. : DSCHR2244QDG5053 - 22 Feb 05
12/16
Specifications subject to change without notice
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