EVB72015-433-FSK-C Melexis Inc, EVB72015-433-FSK-C Datasheet - Page 3

• Manufacturer Part Number: EVB72015-433-FSK-C
• Description: EVAL BOARD 433MHZ FSK/ASK TRANSM
• Manufacturer: Melexis Inc
• Type: Transmitter, ASK, FSKr

Specifications of EVB72015-433-FSK-C

• Frequency: 433MHz
• For Use With/related Products: TH72005, TH72001, TH72002
• Other names: Q3477881D

1 Theory of Operation
1.1 General
As depicted in Fig.1, the TH72015 transmitter consists of a fully integrated voltage-controlled oscillator
(VCO), a divide-by-32 divider (div32), a phase-frequency detector (PFD) and a charge pump (CP). An inter-
nal loop filter determines the dynamic behavior of the PLL and suppresses reference spurious signals. A
Colpitts crystal oscillator (XOSC) is used as the reference oscillator of a phase-locked loop (PLL) synthe-
sizer. The VCO’s output signal feeds the power amplifier (PA). The RF signal power P
four steps from P
voltage V
or to be matched to a 50Ohm load. Bandgap biasing ensures stable operation of the IC at a power supply
range of 1.95 V to 5.5 V.
1.2 Block Diagram
2 Functional Description
2.1 Crystal Oscillator
A Colpitts crystal oscillator with integrated functional capacitors is used as the reference oscillator for the PLL
synthesizer. The equivalent input capacitance CRO offered by the crystal oscillator input pin ROI is about
18pF. The crystal oscillator is provided with an amplitude control loop in order to have a very stable fre-
quency over the specified supply voltage and temperature range in combination with a short start-up time.
39012 72015 01
Rev. 007
CX1
XTAL
CX2
PS
FSKSW
at pin PSEL. The open-collector output (OUT) can be used either to directly drive a loop antenna
ENTX
ROI
out
5
4
3
= –12 dBm to +10 dBm, either by changing the value of resistor RPS or by varying the
XOSC
FSKDTA
control
mode
2
Fig. 1:
XBUF
7
VEE
Block diagram with external components
PLL
PFD
CP
Page 3 of 14
32
VCC
VCO
10
433MHz FSK/ASK Transmitter
RPS
Evaluation Board Description
PSEL
detector
voltage
PA
6
low
ASKDTA
9
VEE
1
8
EVB72015
OUT
out
can be adjusted in
matching
EVB Description
antenna
network
June/07