tda5255e1 Infineon Technologies Corporation, tda5255e1 Datasheet - Page 37

• Manufacturer Part Number: tda5255e1
• Description: Ask/fsk 434mhz Wireless Transceiver
• Manufacturer: Infineon Technologies Corporation

Confidential
3
3.1
3.1.1
Figure 3-1
The RX/TX-switch combines the PA-output and the LNA-input into a single 50 Ohm SMA-
connector. Two pin-diodes are used as switching elements. If no current flows through a pin diode,
it works as a high impedance for RF with very low capacitance. If the pin-diode is forward biased, it
provides a low impedance path for RF. (some W)
3.1.2
The RX/TX-switch is set to the receive mode by either applying a high level or an open to the RX/
TX-jumper on the evalboard or by leaving it open. Then both pin-diodes are not biased and
therefore have a high impedance.
Preliminary Specification
Application
LNA and PA Matching
RX/TX Switch
Switch in RX-Mode
RX/TX Switch
37
TDA5255 E1
Version 1.1
Application
RX/TX_Switch.wmf
2002-11-28