TDA5255XT Infineon Technologies, TDA5255XT Datasheet - Page 40

• Manufacturer Part Number: TDA5255XT
• Manufacturer: Infineon Technologies

Specifications of TDA5255XT

• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Product Depth (mm): 4.4mm
• Product Length (mm): 9.7mm
• Operating Supply Voltage (min): 2.1V
• Operating Supply Voltage (max): 5.5V
• Lead Free Status / Rohs Status: Compliant

The noise figure of the LNA-input-matching network is equal to its losses. The input matching
network is always a compromise of sensitivity and selectivity. The loaded Q should not get too high
because of 2 reasons:
more losses in the matching network and hence less sensitivity
tolerances of components affect matching too much. This will cause problems in a tuning-free mass
production of the application. A good CAE-tool will help to see the effects of component tolerances
on the input matching more accurate by tweaking each value.
A very high selectivity can be reached by using SAW-filters at the expense of higher cost and lower
sensitivity which will be reduced by the losses of the SAW-Filter of approx. 4dB.
Image-suppression:
Due to the quite high 1
frequency of the receiver is at:
The image suppression on the evalboard is about 16dB.
LO-leakage:
The LO of the 1
The LO-leakage of the evalboard on the RF-input is about –102dBm. This is far below the ETSI-
radio-regulation-limit for LO-leakage.
3.1.3
The evalboard can be set into the TX-Mode by grounding the RX/TX-jumper on the evalboard or
programming the TDA5255 to operate in the TX-Mode. If the IC is programmed to operate in the
TX-Mode, the RX/TX-pin will act as an open drain output at a logical LOW. Then a DC-current can
flow from VCC to GND via L1, L2, D1, R1 and D2.
Data Sheet
I
f
PIN
LO
f
IMAGE
−
=
DIODE
f
RECEIVE
=
=
Switch in TX-Mode
f
Vcc
SIGNAL
st
*
4
3
Mixer is at:
=
−
434
2
+
∗
2
2 ,
st
V
*
MHz
-IF of the frontend, the image frequency is quite far away. The image
FORWARD
f
R
IF
1
*
=
4
3
434
=
,
PIN
578
2 ,
−
9 ,
DIODE
MHz
MHz
+
2
*
144
40
7 ,
=
723
7 ,
MHz
TDA5255 E1
Version 1.2
Application
2007-02-26
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