ATA5811 ATMEL Corporation, ATA5811 Datasheet - Page 21

• Manufacturer Part Number: ATA5811
• Description: Ata5811 Uhf Ask/fsk Transceiver
• Manufacturer: ATMEL Corporation

5.14
4689F–RKE–08/06
RX/TX Switch
Table 5-9.
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
10,
element values have to be found on board.
equivalent circuit of the switch. The principal switching operation is described here according to
the application of
Table 5-10.
Figure 5-11. Equivalent Circuit of the Switch
Table 5-7 on page
T
T
T
amb
amb
amb
433.92
Frequency
868.3
315
VS =
= +105°C
= –40°C
= +25°C
MHz
MHz
MHz
Measurements of Typical Output Power Relative to 3V/25°
Impedance of the RX/TX Switch RX_TX2 Shorted to GND
Figure 2-1 on page
20,
Table 5-10
–2.4 dB
–1.6 dB
–2.4 dB
Z(RX_TX1) TX Mode
2.4V
2.5 pF
6. The application of
(4.8 + j3.2)
(4.5 + j4.3)
and
11
(5 + j9)
Table 5-11 on page 22
RX_TX1
1.6 nH
Figure 5-11 on page 21
TX
5
–0.7 dB
–0.8 dB
3.0V
0 dB
Figure 3-1 on page 7
ATA5811/ATA5812
should be used, but the exact
Z(RX_TX1) RX Mode
shows an approximate
(11.3 – j214)
(10.3 – j153)
(8.9 – j73)
Table 5-1 on page
works similarly.
+0.9 dB
+0.1 dB
3.6V
0 dB
21