adl5386 Analog Devices, Inc., adl5386 Datasheet - Page 27

• Manufacturer Part Number: adl5386
• Description: 50 Mhz To 2200 Mhz Quadrature Modulator With Integrated Detector And Vva
• Manufacturer: Analog Devices, Inc.

SPECTRAL PRODUCTS FROM HARMONIC MIXING
For broadband applications, such as cable TV head-end
modulators, special attention must be paid to harmonics of the
LO. Figure 50 shows the level of these harmonics (out to 3 GHz)
as a function of the output frequency from 125 MHz to 1000 MHz,
in a single-sideband (SSB) test configuration, with a baseband
signal of 1 MHz and a SSB level of approximately 0 dBm. To read
this plot correctly, first pick the output frequency of interest on the
trace called P
harmonic traces at multiples of this frequency. For example, at
an output frequency of 500 MHz, the fundamental power is
0 dBm. The power of the second (P
harmonics is −57 dBm (at 1000 MHz) and −11 dBm (at
1500 MHz), respectively. Of particular importance are the
products from odd harmonics of the LO, generated from
the switching operation in the mixers.
For cable TV operation at frequencies above approximately
500 MHz, these harmonics fall out of the band and can be
filtered by a fixed filter. However, as the frequency drops
below 500 MHz, these harmonics start to fall close to or inside
the cable band. This calls for either limitation of the frequency
range to above 500 MHz or the use of a switchable filter bank
to block in-band harmonics at low frequencies.
–10
–20
–30
–40
–50
–60
–70
–80
10
0
100
Figure 50. Spectral Components for Output Frequencies
OUT
200
. The associated harmonics can be read off the
300
from 125 MHz to 1000 MHz
OUTPUT FREQUENCY (MHz)
400
P
6LO – BB
P
7LO + BB
500
600
2fc − BB
P
5LO – BB
) and third (P
700
P
800
4LO + BB
P
2LO – BB
P
OUT
P
900
3LO + BB
3fc + BB
1000
)
Rev. 0 | Page 27 of 36
LO GENERATION USING PLLs
Analog Devices has a line of PLLs that can be used for generating
the LO signal. Table 6 lists the PLLs together with their maximum
frequency and phase noise performance.
Table 6. PLL Selection Table
Model
ADF4002
ADF4106
ADF4110
ADF4111
ADF4112
ADF4113
ADF4116
ADF4117
ADF4118
The ADF4360-x comes as a family of chips, with nine operating
frequency ranges. One can be chosen depending on the local
oscillator frequency required. While the use of the integrated
synthesizer may come at the expense of slightly degraded noise
performance from the ADL5386, it can be a cheaper alternative
to a separate PLL and VCO solution. Table 7 shows the options
available. An up-to-date list of available PLLs can be found at
www.analog.com/pll.
Table 7. ADF4360-x Family Operating Frequencies
Model
ADF4360-0
ADF4360-1
ADF4360-2
ADF4360-3
ADF4360-4
ADF4360-5
ADF4360-6
ADF4360-7
ADF4360-8
ADF4360-9
Frequency f
400
6000
550
1200
3000
4000
550
1200
3000
Output Frequency Range (MHz)
2400 to 2725
2050 to 2450
1850 to 2150
1600 to 1950
1450 to 1750
1200 to 1400
1050 to 1250
350 to 1800
65 to 400
1.1 to 200 (using auxiliary dividers)
IN
(MHz)
At 1 kHz Phase Noise
dBc/Hz, 200 kHz PFD
−103 @ 400 MHz
−93 @ 900 MHz
−91 @ 540 MHz
−87@ 900 MHz
−90 @ 900 MHz
−91 @ 900 MHz
−89 @ 540 MHz
−87 @ 900 MHz
−90 @ 900 MHz
ADL5386