tda5255e1 Infineon Technologies Corporation, tda5255e1 Datasheet - Page 41

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

Confidential
Now both pin-diodes are biased with a current of approx. 0.3mA@3V and have a very low
impedance for RF.
Figure 3-4
R1 does not influence the matching because of its very high resistance. Due to the large
capacitance of C1, C6 and C5 the circuit can be further simplified for RF:
Figure 3-5
The LNA-matching is RF-grounded now, so no power is lost in the LNA-input. The PA-matching
consists of C2, C3 L2, C4 and L1.
When designing the matching of the PA, C2 must not be changed anymore because its value is
already fixed by the LNA-input-matching.
Preliminary Specification
TX_Mode
TX_Mode_simplified
41
TDA5255 E1
TX_Mode_simplified.wmf
Version 1.1
Application
2002-11-28
TX_Mode.wmf