AXM0F243 datasheet(23/53 Pages) ONSEMI

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AXM0F243

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Table 39. RF FREQUENCY GENERATION SUBSYSTEM (SYNTHESIZER)

Symbol

Description

Condition

Min

Typ

Max

Units

fREF

Reference frequency

The reference frequency must be chosen

so that the RF carrier frequency is not an

integer multiple of the reference frequency

MHz

Dividers

NDIVref

Reference divider ratio range

Controlled directly with bits REFDIV in reg-

ister AX5043_PLLVCODIV

NDIVm

Main divider ratio range

Controlled indirectly with register

AX5043_FREQ

4.5

66.5

NDIVRF

RF divider range

Controlled directly with bit RFDIV in regis-

ter AX5043_ PLLVCODIV

Charge Pump

ICP

Charge pump current

Programmable in increments of 8.5 mA via

8.5

2168

Internal VCO (VCOSEL = 0)

fRF

RF frequency range

RFDIV = 1

400

525

MHz

RFDIV = 0

800

1050

fstep

RF frequency step

RFDIV = 1

fREF = 16.000000 MHz

0.98

Synthesizer loop bandwidth

The synthesizer loop bandwidth an start−

up time can be programmed with the reg-

isters AX5043_PLLLOOP and

AX5043_PLLCPI.

For recommendations see the AX5043

Programming Manual, the AX−RadioLab

software and AX5043 Application Notes

on compliance with regulatory regimes.

500

kHz

Tstart

Synthesizer start−up time if crystal

oscillator and reference are running

PN868

Synthesizer phase noise 868 MHz

fREF = 48 MHz

10 kHz from carrier

−95

dBc/Hz

1 MHz from carrier

−120

PN433

Synthesizer phase noise 433 MHz

fREF = 48 MHz

10 kHz from carrier

−105

dBc/Hz

1 MHz from carrier

−120

VCO with external inductors (VCOSEL = 1, VCO2INT = 1)

fRFrng_lo

RF frequency range

For choice of Lext values as well as

VCO gains see Figure 3 and

Figure 4

RFDIV = 1

262

MHz

fRFrng_hi

RFDIV = 0

525

PN169

Synthesizer phase noise 169 MHz

Lext=47 nH (wire wound 0603)

AX5043_RFDIV = 0, fREF= 16 MHz

Note: phase noises can be im-

proved with higher fREF

10 kHz from carrier

−97

dBc/Hz

1 MHz from carrier

−115

External VCO (VCOSEL = 1, VCO2INT = 0)

fRF

RF frequency range fully external

VCO

Note: The external VCO frequency needs

to be 2 x fRF

1000

MHz

Vamp

Differential input amplitude at L1, L2

terminals

0.7

VinL

Input voltage levels at L1, L2 termi-

nals

1.8

Vctrl

Control voltage range

Available at FILT in external loop filter

mode

1.8

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