TDA5235 Datasheet, PDF (21/259 Pages) Infineon Technologies AG – Enhanced Sensitivity Double-Configuration Receiver with Digital Baseband Processing

TDA5235
Functional Description
I-Mix
RX
Input
LNA
Q-Mix
1^st LO
CER-
Filter
IF1
10.7 MHz
IF
Attenuation
adjust
RX
I-
LP
digital ^{FSK Data}
Mix2
harm sup FSK Demod
RX
Q-
Mix2
RSSI Generator
LP
alias sup
ASK /
RSSI
ADC
ASK Data
Channel Filter
Bandwidth select
Divider
:N
2^nd LO
Figure 5 Double Down Conversion (DDC) with one external filter
For applications which demand very high selectivity and/or channel separation even two
CER filters may be used. Also in applications where one configuration/channel requires
a wider bandwidth than the other (e.g. TPMS and RKE) the second filter can be by-
passed.
RX
Input
LNA
I-Mix
Q-Mix
1^st LO
CER-
Filter
IF1
10.7 MHz
IF
Attenuation
adjust
CER-
Filter IF1
10.7 MHz
optional
RX
I-
LP
digital ^{FSK Data}
Mix2
harm sup FSK Demod
RX
Q-
Mix2
RSSI Generator
LP
alias sup
ASK /
RSSI
ADC
ASK Data
Channel Filter
Bandwidth select
Divider
:N
2^nd LO
Figure 6 Double Down Conversion (DDC) with two external filters
Data Sheet
21
V1.0, 2010-02-19