TH71102 Datasheet, PDF (4/22 Pages) List of Unclassifed Manufacturers – FSK/FM/ASK Receiver

1.3 Block Diagram
TH71102
315/433MHz
FSK/FM/ASK Receiver
12
34
5
6
7
8
9 10 11 12 13
21
14 15
16
IN_LNA
31
LNA
32 30
MIX1
MIX2
IF1
IF2
IFA
LO1
LO2
MIX3
DIV8
DIV2
PFD
RO
VCO1
CP
BIAS
29 LF
26 RO
25 27
28
Fig. 1: TH71102 block diagram
22
17
OUTP
23
OUTN
24
OAP
OA
20
OAN
19
OUT_OA
18
1.4 Mode Configurations
ENRX
Mode
0
RX standby
1
RX active
Note: ENRX are pulled down internally
Description
RX disabled
RX enable
1.5 LNA GAIN Control
V_{GAIN_LNA}
< 0.8 V
Mode
HIGH GAIN
> 1.4 V
LOW GAIN
Note: hysteresis between gain modes to ensure stability
Description
LNA set to high gain
LNA set to low gain
1.6 Frequency Planning
Frequency planning is straightforward for single-conversion applications because there is only one IF that
can be chosen, and then the only possible choice is low-side or high-side injection of the LO signal (which is
now the one and only LO signal in the receiver).
The receiver’s double-conversion architecture requires careful frequency planning. Besides the desired RF
input signal, there are a number of spurious signals that may cause an undesired response at the output.
Among them are the image of the RF signal (that must be suppressed by the RF front-end filter), spurious
signals injected to the first IF (IF1) and their images which could be mixed down to the same second IF (IF2)
as the desired RF signal (they must be suppressed by the LC filter at IF1 and/or by low-crosstalk design).
39010 71102
Rev. 013
Page 4 of 22
Data Sheet
June/07