ADRF6614ACPZ-R7 datasheet(43/61 Pages) AD

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Data Sheet

ADRF6614

Rev. 0 | Page 43 of 61

GSM MODE OF OPERATION

The ADRF6614 supports GSM phase noise specifications in

typical GSM bands such as the 800 MHz, 900 MHz, 1800 MHz,

and 1900 MHz. GSM phase noise performance in the 800 MHz

and 900 MHz bands is met by simply tuning the integrated

PLLVCO to the desired frequency.

Integrated VCO cores (VCO_4 and VCO_5) support GSM phase

noise performance in the 1800 MHz and 1900 MHz GSM bands.

To ensure that GSM phase noise performance is achieved when

using the ADRF6614 in 1800 MHz or 1900 MHz bands, select

the VCO_4 core by writing the VCO_SEL bits in the VCO_

CTRL1 register (Register 0x22, Bits[2:0]) for a frequency range

of 1.525 GHz to 1.547 GHz, and the VCO_5 core for a frequency

range of 1.668 GHz to 1.708 GHz.

The VCO_4 and VCO_5 cores operate at fundamental frequencies

of 3.050 GHz to 3.094 GHz and 3.336 GHz to 3.416 GHz, respec-

tively. To generate the desired LO frequency in the 1800 MHz

and 1900 MHz bands, enable divide by 2 by writing to LO_DIV

(Register 0x22, Bits[5:3]).

For the GSM mode of operation, the recommended loop filter

components and dynamic loop settings are shown in Table 19 at

the PFD rate of 1.536 MHz.

See Figure 118 for the GSM mode phase noise performance

of −145 dBc/Hz at 800 kHz offset at the carrier frequency of

1.535 GHz.

When using the VCO_4 or VCO_5 cores, it is required to

set VTUNE_DAC_SLOPE (Register 0x49, Bits[13:9]) = 9d,

VTUNE_DAC_OFFSET (Register 0x49, Bits[8:0]) = 171d,

VCO_LDO_R2 (Register 0x22, Bits[11:8]) = 2d, and VCO_

LDO_R4 (Register 0x22, Bits[15:12]) = 10d. In transitioning

from a GSM VCO (VCO_4 and VCO_5) to an octave VCO, the

LDO settings must be changed before changing the VCO

selection.

–180

–20

–30

–40

–50

–60

–70

–80

–90

–100

–110

–120

–130

–140

–150

–160

–170

FREQUENCY (Hz)

10k

100k

10M

100M

1: 1kHz

–88.8656dBc/Hz

2: 10kHz

–91.0102dBc/Hz

3: 50kHz

–111.8226dBc/Hz

4: 100kHz

–121.2806dBc/Hz

5: 500kHz

–141.0461dBc/Hz

6: 800kHz

–145.2453dBc/Hz

7: 1MHz

–148.3557dBc/Hz

8: 10MHz

–158.4950dBc/Hz

9: 40MHz

–158.6742dBc/Hz

10: 100MHz –157.3591dBc/Hz

START: 500Hz

STOP: 20MHz

CENTER: 10.00025MHz

SPAN: 19.9995MHz

INTG NOISE: –47.5392dBc/19.7MHz

RMS NOISE: 5.93684 mrad

340.156mdeg

RMS JITTER: 615.168fs

RESIDUAL FM: 866.159Hz

Figure 118. GSM Phase Noise Performance at 1.535 GHz

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