TH72011

433MHz

FSK Transmitter

3901072011

Page 3 of 20

Data Sheet

Rev. 011

Jun/12

1 Theory of Operation

1.1

General

As depicted in Fig.1, the TH72011 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

internal 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)

loop antenna 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

Fig. 1: Block diagram with external components

CX1

FSKDTA

antenna

matching

network

VEE

XOSC

low

voltage

detector

PA

XBUF

VCO

PLL

CP

PFD

32

OUT

PSEL

RPS

FSKSW

ROI

XTAL

CX2

8

1

7

5

3

2

mode

control

ENTX

4

6

VCC