ATA5423_06 ATMEL [ATMEL Corporation], ATA5423_06 Datasheet - Page 23

• Manufacturer Part Number: ATA5423_06
• Description: UHF ASK/FSK Transceiver
• Manufacturer: ATMEL [ATMEL Corporation]

3.14
4841C–WIRE–05/06
RX/TX Switch
Table 3-9
3.0V/25°C. As can be seen, a temperature change to –40°C as well as to +85°C reduces the
power by less than 1 dB due to the band gap regulated output current. Measurements of all the
cases in
relative behavior as shown in
Table 3-9.
The RX/TX switch decouples the LNA from the PA in TX mode, and directs the received power
to the LNA in RX mode. To do this, it has a low impedance to GND in TX mode and a high
impedance to GND in RX mode. To design a proper RX/TX decoupling, a linear simulation tool
for radio frequency design together with the measured device impedances of
11,
element values have to be found on-board.
of the switch. The principal switching operation is described here according to the application of
Figure 2-1 on page
Table 3-10.
Figure 3-11. Equivalent Circuit of the Switch
Table 3-7 on page
T
T
T
amb
amb
amb
433.92
868.3
Frequency
Table 3-7 on page 22
315
345
915
VS =
=
= +25°C
= +85°C
shows the relative changes of the output power of a typical device compared to
–
MHz
MHz
MHz
40°C
MHz
MHz
Measurements of Typical Output Power Relative to 3V/25°C
Impedance of the RX/TX Switch RX_TX2 Shorted to GND
7. The application of
22,
Table 3-10
Table
over temperature and supply voltage have shown about the same
–
–
–
2.4 dB
1.6 dB
2.3 dB
Z(RX_TX1) TX Mode
2.4V
3-9.
2.5 pF
(4.8 + j3.2)Ω
(4.7 + j3.4)Ω
(4.5 + j4.3)Ω
11 Ω
and
(5 + j9.2)Ω
(5 + j9)Ω
Figure 2.2 on page 8
Table 3-11 on page 24
Figure 3-11
1.6 nH
RX_TX1
TX
shows an approximate equivalent circuit
5 Ω
–
–
0.7 dB
0.7 dB
3.0V
0 dB
ATA5423/25/28/29
works similarly.
should be used, but the exact
Z(RX_TX1) RX Mode
(11.3
(11.1
(10.3
(8.9
(9
–
–
–
–
–
Table 3-1 on page
j65)Ω
j214)Ω
j181)Ω
j153)Ω
j73)Ω
+0.9 dB
+0.4 dB
3.6V
0 dB
23