MLX71120KLQ Melexis Inc, MLX71120KLQ Datasheet - Page 10

• Manufacturer Part Number: MLX71120KLQ
• Description: RCVR FSK/FM/ASK 32-QFN
• Manufacturer: Melexis Inc

Specifications of MLX71120KLQ

• Frequency: 300MHz ~ 930MHz
• Sensitivity: -108dBm
• Data Rate - Maximum: 100 kbps
• Modulation Or Protocol: ASK, FM, FSK
• Applications: General Remote Control, Garage Opener, RKE
• Current - Receiving: 8.1mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Features: RSSI Equipped
• Voltage - Supply: 2.1 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 32-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Memory Size: -
• Other names: MLX71120A

1.13 Data Filter
The data filter is formed by the operational amplifier OA1, two internal 100kΩ resistors and two external ca-
pacitors. It is implemented as a 2
higher frequencies and therefore leads to an increased sensitivity.
The filter’s pole locations can be set by the external capacitors CF1 and CF2. The cut-off frequency f
be adjusted according to the transmission data rate R. It should be set to approximately 1.5 times the fast-
est expected data rate. For a Butterworth filter characteristic, the data filter capacitors can be calculated as
follows.
1.14 Data Slicer
The purpose of the data slicer is to convert the filtered data signal into a digital output. It can therefore be
considered as an analog-to-digital converter. This is done by using the operational amplifier OA2 as a com-
parator that compares the data filter output with a threshold voltage. The threshold voltage can be derived in
two different ways from the data signal.
39010 71120
Rev. 006
R
RZ
[kbit/s]
0.6
1.2
1.6
2.4
3.3
4.8
6.0
SLCSEL
0
1
CF1
=
100k
CF1
DF1
R
NRZ
2
⋅
1.2
2.4
3.2
4.8
6.6
9.6
12
[kbit/s]
π
100k
nd
⋅
1
100k
order Sallen-Key filter. The low pass filter characteristic rejects noise at
DF2
OA1
CF2
⋅
f
data filter
c
Page 10 of 30
fc [kHz]
DF0
0.9
1.8
2.4
3.6
7.2
5
9
Averaging detection mode
Peak detection mode
Fig. 5:
Description
CF2 =
CF1 [pF]
Data filter
2200
1200
1000
680
470
330
220
CF1
FSK/FM/ASK Receiver
2
MLX71120
300 to 930MHz
CF2 [pF]
1000
680
470
330
220
150
100
Data Sheet
c
Jun/08
has to