EVB71101B-418-FSK-C Melexis Inc, EVB71101B-418-FSK-C Datasheet - Page 5

• Manufacturer Part Number: EVB71101B-418-FSK-C
• Description: EVALUATION BOARD TH71101 RECEIVR
• Manufacturer: Melexis Inc
• Type: Receiver, ASK/FSKr

Specifications of EVB71101B-418-FSK-C

• Rohs Status: RoHS non-compliant
• Frequency: 418MHz
• For Use With/related Products: TH71101
• Other names: EVB71101-418-FSK; EVB71101-418-FSK; EVB71101-418F; EVB71101-418F; EVB71101B-418FSKC

By using the internal PLL synthesizer of the TH71101 with the fixed feedback divider ratio of N = 16
(DIV_16), two types of down-conversion are possible: low-side injection of LO and high-side injection of LO.
The following table summarizes some equations that are useful to calculate the crystal reference frequency
(REF) and the LO frequency, for a given RF and IF.
1.6.1 Selected Frequency Plans
The following table depicts crystal, LO and image signals considering the examples of 315 MHz and
433.92 MHz RF reception at IF = 10.7 MHz.
The selection of the reference crystal frequency is based on some assumptions. As for example: the image
frequency should not be in a radio band where strong interfering signals might occur (because they could
represent parasitic receiving signals), the LO signal should be in the range of 300 MHz to 450 MHz (because
this is the optimum frequency range of the VCO1). Furthermore the IF should be as high as possible to
achieve highest RF image rejection. The columns in bold depict the selected frequency plans to receive at
315 MHz and 433.92 MHz, respectively.
1.6.2 Maximum Frequency Coverage
39012 71101 01
Rev. 012
RF image / MHz
Injection type
Signal type
REF / MHz
LO / MHz
Injection type
Injection type
Parameter
REF / MHz
RF image
RF / MHz
LO / MHz
IF/ MHz
REF
LO
IF
RF = 315 MHz
19.01875
304.3
293.6
low
RF = 315 MHz
(RF – IF)/16
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16 • REF
20.35625
RF – 2IF
RF – LO
325.7
336.4
289.3
18.75
high
10.7
high
low
300
f
min
Evaluation Board Description
RF = 433.92 MHz
26.45125
423.22
412.52
low
315/433MHz Receiver
EVB71101
(RF + IF)/16
16 • REF
RF + 2IF
LO – RF
28.125
460.7
high
10.7
f
450
RF = 433.92 MHz
low
max
EVB Description
27.78875
444.62
455.32
high
April/08