th71101 Melexis Company, th71101 Datasheet - Page 4

• Manufacturer Part Number: th71101
• Description: Receiver - 315/433mhz Fsk/ask, Single-conversion Superhet Lqfp32
• Manufacturer: Melexis Company

1.3
1.4
Note: ENRX are pulled down internally
1.5
Note: hysteresis between gain modes to ensure stability
1.6
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 single-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 is the image of the RF signal that must be suppressed by the RF front-end filter.
39010 71101
Rev. 015
Block Diagram
Mode Configurations
LNA GAIN Control
Frequency Planning
V
< 0.8 V
> 1.4 V
IN_LNA
31
ENRX
GAIN_LNA
32
1
0
1
LNA
30
2
3
4
VCO1
MIX1
5
LO
HIGH GAIN
DIV_16
RX standby
LOW GAIN
RX active
29
6
Mode
Mode
LF
IF
Fig. 1: TH71101 block diagram
7
CP
MIX2
8
PFD
9
Page 4 of 22
IF
10
26
RO
RO
11
12
25
13
27
IFA
21
28
LNA set to high gain
LNA set to low gain
BIAS
14
Description
Description
RX disabled
RX enable
15
22
FSK/ASK Receiver
MIX3
16
17
TH71101
315/433MHz
OA
OUT_OA
OUTN
OUTP
OAN
OAP
Data Sheet
23
24
20
19
18
April/08