tda5235 Infineon Technologies Corporation, tda5235 Datasheet - Page 19

• Manufacturer Part Number: tda5235
• Description: Enhanced Sensitivity Double-configuration Receiver With Digital Baseband Processing
• Manufacturer: Infineon Technologies Corporation

The frequency relations are calculated with the following formulas:
Figure 3
The front end of the receiver comprises an LNA, an image reject mixer and a digitally
gain controlled buffer amplifier. This buffer amplifier allows the production spread of the
on-chip signal strip, of external matching circuitry and RF SAW and ceramic IF filters to
be trimmed. The second image reject mixer down converts the first IF to the second IF.
Data Sheet
Input
RX
LNA
f
f
f
f
LO1
f
LO2
crystal
IF1
IF2
Q-Mix
I-Mix
=
=
=
=
Block Diagram RF Section
10.7MHz
=
f
f
----------------
f
-------- -
39
crystal
crystal
IF1
f
2
IF2
×
Attenuation
×
adjust
VCO
80
IF
NF
Band select
divider
:1/:2/:3
10 .7 MHz
CER-
Filter
IF1
IQ Divider : 4
Channel select
N
10.7 MHz
Filter IF1
optional
CER-
Divider : N_FN
Multi Modulos
ΣΔ Modulator
19
LF select
Loop
Filter
PD
Crystal
oscil -
IQ :2
Mix2
Mix2
lator
Q-
I-
AFC
Filter
Bandwidth select
RSSI Gain/ Offset adjust
Channel Filter
Functional Description
Channel Filter select
IF Attenuation adjust
Channel select
Band select
RSSI Generator
LF select
V1.0, 2010-02-19
harm sup
alias sup
LP
LP
control unit
Front end
TDA5235
FSK Demod
ASK /
RSSI
ADC
Divider
digital
: N
FSK Data
ASK Data
RX
RX