TDA5204E1 Infineon Technologies, TDA5204E1 Datasheet - Page 16

• Manufacturer Part Number: TDA5204E1
• Description: ASK Single Conversion Receiver 390MHz
• Manufacturer: Infineon Technologies

Wireless Components
RF
3.4.1
DGND
TAGC
3.3 Functional Block Diagram
3.4 Functional Blocks
VDD
14
13
3
4
2/7
VCC
LNA
Figure 3-2
Low Noise Amplifier (LNA)
The LNA is an on-chip cascode amplifier with a voltage gain of 15 to 20dB. The
gain figure is determined by the external matching networks situated ahead of
LNA and between the LNA output LNO (Pin 6) and the Mixer Inputs MI and MIX
(Pins 8 and 9). The noise figure of the LNA is approximately 2dB, the current
consumption is 500µA. The gain can be reduced by approximately 18dB. The
switching point of this AGC action can be determined externally by applying a
threshold voltage at the THRES pin (Pin 23). This voltage is compared internally
with the received signal (RSSI) level generated by the limiter circuitry. In case
that the RSSI level is higher than the threshold voltage the LNA gain is reduced
and vice versa. The threshold voltage can be generated by attaching a voltage
divider between the 3VOUT pin (Pin 24) which provides a temperature stable
3V output generated from the internal bandgap voltage and the THRES pin as
described in Section 4.1. The time constant of the AGC action can be deter-
mined by connecting a capacitor to the TAGC pin (Pin 4) and should be chosen
along with the appropriate threshold voltage according to the intended operat-
5/10
VCC
AGND
LNO
6
MI
8
: 1/2
11
FSEL
MIX IFO
9
12
Main Block Diagram
Filter
Loop
Filter
VCO
IF
LF
15
LIM
17
TDA 5204
: 128/64
3 - 8
LIMX
18
16
CSEL
RSSI
DET
Φ
FFB
22
Crystal
Crystal
OSC
1
28
OPP
21
Reference
Bandgap
U
Reference
REF
AGC
27
PDWN
SLP
19
Specification, December 2000
Functional Description
SLN
20
SLICER
25
26
23
24
3VOUT
DATA
PDO
THRES
TDA 5204 E1
Function_5204.wmf
preliminary