tda5255e1 Infineon Technologies Corporation, tda5255e1 Datasheet - Page 44

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

Confidential
Figure 3-8
C4, L2 and C3||C2 are the main matching components which are used to transform the 50 Ohm
load at the SMA-RF-connector to a higher impedance at the PA-output (250Ohm@3V). L1 can be
used for finetuning of the resonance frequency but should not be too low in order to keep its loss
low.
The transformed impedance of 250Ohm+j0 at the PA-output-pin can be verified with a network
analyzer using this measurement procedure:
1. Calibrate your network analyzer.
2. Connect a short, low-loss 50 Ohm cable to your network analyzer with an open end on one side.
3. Use the „Port Extension“ feature of your network analyzer to shift the reference plane of your
4. Connect the center-conductor of the cable to the solder pad of the pin „PA“ of the IC. The shield
5. Screw a 50Ohm-dummy-load on the RF-I/O-SMA-connector
6. The TDA5255 has to be in ASK-TX-Mode, Data-Input=LOW.
7. Be sure that your network analyzer is AC-coupled and turn on the power supply of the IC.
8. Measure the S-parameter
Preliminary Specification
Semirigid cable works best.
network analyzer to the open end of the cable.
has to be grounded. Very short connections must be used. Do not remove the IC or any part of
the matching-components!
Power output and collector current vs. frequency
44
TDA5255 E1
Version 1.1
pout_vs_frequ_434.wmf
Application
2002-11-28