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参数资料
| 型号： | ADL5374ACPZ-WP |
| 厂商： | ANALOG DEVICES INC |
| 元件分类： | 调制器/解调器 |
| 英文描述： | 3000 MHz - 4000 MHz RF/MICROWAVE QUADRAPHASE MODULATOR |
| 封装： | 4 X 4 MM, ROHS COMPLIANT, MO-220VGGD-2, LFCSP-24 |
| 文件页数： | 5/20页 |
| 文件大小： | 855K |
| 代理商： | ADL5374ACPZ-WP |
ADL5374
Rev. 0 | Page 13 of 20
OPTIMIZATION
The carrier feedthrough and sideband suppression performance of
the ADL5374 can be improved by using optimization techniques.
Carrier Feedthrough Nulling
Carrier feedthrough results from minute dc offsets that occur
between each of the differential baseband inputs. In an ideal
modulator, the quantities (VIBBP VIBBN) and (VQBBP VQBBN) are
equal to zero, which results in no carrier feedthrough. In a real
modulator, those two quantities are nonzero and, when mixed
with the LO, result in a finite amount of carrier feedthrough. The
ADL5374 is designed to provide a minimal amount of carrier
feedthrough. Should even lower carrier feedthrough levels be
required, minor adjustments can be made to the (VIBBP VIBBN)
and (VQBBP V QBBN) offsets. The I-channel offset is held constant,
while the Q-channel offset is varied until a minimum carrier
feedthrough level is obtained. The Q-channel offset required to
achieve this minimum is held constant, while the offset on the
I-channel is adjusted until a new minimum is reached. Through
two iterations of this process, the carrier feedthrough can be
reduced to as low as the output noise. The ability to null is
sometimes limited by the resolution of the offset adjustment.
Figure 26 shows the relationship of carrier feedthrough vs. dc
offset as null.
–60
–88
–84
–80
–76
–72
–68
–64
–300 –240 –180 –120 –60
0
60
120
180
240
300
06
62
7-
02
6
CA
RRI
E
R
F
E
DT
HRO
U
G
H
(
d
Bm
)
VP – VN OFFSET (V)
Figure 26. Carrier Feedthrough vs. DC Offset Voltage at 3500 MHz
Note that throughout the nulling process, the dc bias for the
baseband inputs remains at 500 mV. When no offset is applied,
VIBBP = VIBBN = 500 mV, or
VIBBP VIBBN = VIOS = 0 V
When an offset of +VIOS is applied to the I-channel inputs,
VIBBP = 500 mV + VIOS/2, and
VIBBN = 500 mV VIOS/2, such that
VIBBP VIBBN = VIOS
The same applies to the Q channel.
It is often desirable to perform a one-time carrier null calibra-
tion. This is usually performed at a single frequency. Figure 27
shows how carrier feedthrough varies with LO frequency over a
range of ±50 MHz on either side of a null at 3500 MHz.
CAR
RI
E
R
F
E
DT
HRO
UG
H
(
d
B
m
)
LO FREQUENCY (MHz)
06
62
7-
0
27
–80
–75
–70
–65
–60
–55
–50
–45
–40
–35
–30
3450 3460 3470 3480 3490 3500 3510 3520 3530 3540 3550
Figure 27. Carrier Feedthrough vs. fLO After Nulling at 3500 MHz
Sideband Suppression Optimization
Sideband suppression results from relative gain and relative
phase offsets between the I-channel and Q-channel and can
be suppressed through adjustments to those two parameters.
Figure 28 illustrates how sideband suppression is affected by
the gain and phase imbalances.
0dB
0.0125dB
0.025dB
0.05dB
0.125dB
0.25dB
0.5dB
1.25dB
2.5dB
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
0.01
0.1
1
10
100
S
IDE
BA
ND
S
UP
P
RE
S
IO
N
(
d
Bc)
PHASE ERROR (Degrees)
0
662
7-
0
28
Figure 28. Sideband Suppression vs. Quadrature Phase Error for
Various Quadrature Amplitude Offsets
Figure 28 underlines the fact that adjusting only one parameter
improves the sideband suppression only to a point, unless the
other parameter is also adjusted. For example, if the amplitude
offset is 0.25 dB, improving the phase imbalance by better than
1° does not yield any improvement in the sideband suppression.
For optimum sideband suppression, an iterative adjustment
between phase and amplitude is required.
The sideband suppression nulling can be performed either
through adjusting the gain for each channel or through the
modification of the phase and gain of the digital data coming
from the digital signal processor.
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相关代理商/技术参数 |
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| ADL5375 | 制造商:AD 制造商全称:Analog Devices 功能描述:400 MHz to 6 GHz Broadband Quadrature Modulator |
| ADL5375_13 | 制造商:AD 制造商全称:Analog Devices 功能描述:400 MHz to 6 GHz Broadband Quadrature Modulator |
| ADL5375-05 | 制造商:AD 制造商全称:Analog Devices 功能描述:Interfacing the ADL5375 I/Q Modulator to the AD9779A Dual-Channel, 1 GSPS High Speed DAC |
| ADL5375-05ACPZ | 制造商:Analog Devices 功能描述:IC 400MHZ-6GHZ MOD QUAD 24LFCSP 制造商:Analog Devices 功能描述:IC, 400MHZ-6GHZ, MOD, QUAD, 24LFCSP 制造商:Analog Devices 功能描述:IC, 400MHZ-6GHZ, MOD, QUAD, 24LFCSP; Frequency Min:400MHz; Frequency Max:6GHz; RF Type:Quadrature; Supply Voltage Min:4.75V; Supply Voltage Max:5.25V; RF IC Case Style:LFCSP; No. of Pins:24; Operating Temperature Min:-40C; Operating;RoHS Compliant: Yes 制造商:Analog Devices 功能描述:Quadrature Mod 24-Pin LFCSP EP T/R |
| ADL5375-05ACPZ-R2 | 制造商:Analog Devices 功能描述:400 MHZ TO 6 GHZ BROADBAND QUADRATURE MODULATOR - Tape and Reel |
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