EVB72016-915-ASK-A 参数 Datasheet PDF下载

EVB72016

433MHz FSK/ASK Transmitter

Evaluation Board Description

1 Theory of Operation

1.1 General

As depicted in Fig.1, the TH72016 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

out

can be adjusted in

four steps from P

out

= –12 dBm to +10 dBm, either by changing the value of resistor RPS or by varying the

voltage V

PS

at pin PSEL. The open-collector output (OUT) can be used either to directly drive a loop antenna

or to be matched to a 50 Ohm 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

RPS

CKDIV

VCC

PSEL

R1

ASKDTA

7

10

6

8

PLL

CKOUT

5

div 4

div 16

32

PA

OUT

antenna

matching

network

ROI

3

XTAL

FSKSW

CX2

CX1

2

1

FSKDTA

PFD

XOSC

XBUF

CP

VCO

mode

control

4

EN

9

VEE

Fig. 1:

Block diagram with external components

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

18 pF. 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.

3901272016 01

Rev. 004

Page 3 of 12

EVB Description

June/07