MLX71121KLQ Melexis Inc, MLX71121KLQ Datasheet - Page 13

• Manufacturer Part Number: MLX71121KLQ
• Description: RCVR FSK/FM/ASK 32-QFN
• Manufacturer: Melexis Inc

Specifications of MLX71121KLQ

• 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
• Data Rate: 100Kbps
• Frequency Range: 300MHz To 930MHz
• Modulation Type: AM, FM, FSK
• Rf Ic Case Style: QFN
• No. Of Pins: 32
• Supply Voltage Range: 2.1V To 5.5V
• Operating Temperature Range: -40°C To
• Sensitivity Dbm: -112dBm
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Memory Size: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: MLX71121A

2
2.1
Because of the double conversion architecture that employs two mixers and two IF signals, there are four
different combinations for injecting the LO1 and LO2 signals:
As a result, four different radio frequencies (RFs) could yield one and the same second IF (IF2). Fig. 10
shows this for the case of receiving at f
high) and f
bandpass shape can be achieved either with a SAW filter (featuring just a couple of MHz bandwidth), or by
the tank circuits at the LNA input and output (this typically yields 30 to 60MHz bandwidth). In any case, the
high value of the first IF (IF1) helps to suppress the image signals at f
The two remaining signals at IF1 resulting from f
mixer MIX2. This mixer features image rejection with so-called single-sideband (SSB) selection. This means
either the upper or lower sideband of IF1 can be selected. In the example of Fig. 10, LO2 high-side injection
has been chosen to select the IF2 signal resulting from f
It can be seen from the block diagram of Fig. 1 that there is a fixed relationship between the LO signal fre-
quencies (f
The operating frequency of the internal IF filter (IFF) and FSK demodulator (FSK DEMOD) are 1.8MHz.
Therefore the second IF (IF2) is set to 1.8MHz as well.
39010 71121
Rev. 009
Functional Description
Frequency Planning
LO1
RF
•
•
•
•
(low-low) are suppressed by the bandpass characteristic provided by the RF front-end. The
Fig. 10: The four receiving frequencies in a double conversion superhet receiver
, f
LO2
LO1 high side and LO2 high side:
LO1 high side and LO2 low side:
LO1 low side and LO2 high side:
LO1 low side and LO2 low side:
f
RF
) and the reference oscillator frequency f
f
LO1
=
f
N
RF
1
⋅
f
RF
f
LO2
LO2
(high-high). In the example of Fig. 10, the image signals at f
Page 13 of 28
RF
(high-high) and f
f
LO1
RF
receiving at f
receiving at f
receiving at f
receiving at f
(high-high).
RO
.
f
LO2
f
LO2
RF
RF
RF
RF
RF
=
RF
(low-high) and f
(high-high)
(high-low)
(low-high)
(low-low)
(high-low) are entering the second
N
f
2
FSK/FM/ASK Receiver
RF
⋅
f
RO
MLX71121
RF
300 to 930MHz
(low-low).
f
RF
Data Sheet
RF
Oct/10
(low-