CHR2244-QDG_15 Datasheet, PDF (11/14 Pages) United Monolithic Semiconductors – 5.8 GHz One Antenna Reflective Transponder for Tag

5.8 GHz One Antenna Reflective Tag
CHR2244-QDG
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 (figures 2a; 2B and 2c) 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
Det
AM
modulated
RF-in
AM
modulated
T/R
0V
DATA_out
WK_in
0V
SB_out
SB_out
to controller
Vcc
Figure 2a: Standby mode
The received AM modulated RF spectrum is the following (figure 2b), 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
5.79 95GHz
5.80 05GHz
m=0.5
5.79 95GHz
5.80 05GHz
m=0.7
5.7995GHz
5.80 05GHz
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. :DSCHR2244-QDG9030 - 30 Jan 09
11/14
Specifications subject to change without notice
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