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參數(shù)資料
| 型號： | ADL5371ACPZ-R2 |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 調(diào)制器/解調(diào)器 |
| 英文描述： | 700 MHz - 1300 MHz RF/MICROWAVE QUADRAPHASE MODULATOR |
| 封裝： | LEAD FREE, MO-220VGGD-2, LFCSP-24 |
| 文件頁數(shù)： | 4/20頁 |
| 文件大?。?/td> | 930K |
| 代理商： | ADL5371ACPZ-R2 |
ADL5371
Rev. 0 | Page 12 of 20
OPTIMIZATION
The carrier feedthrough and sideband suppression performance
of the ADL5371 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 (VIOPP VIOPN) and (VQOPP VQOPN)
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, they result in a finite amount of carrier feedthrough.
The ADL5371 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 (VIOPP VIOPN)
and (VQOPP VQOPN) 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 24 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
0
651
0-
02
5
CARRI
E
R
F
E
D
T
HRO
UG
H
(d
Bm
)
VP – VN OFFSET (V)
Figure 24. Typical Carrier Feedthrough vs. DC Offset Voltage
Note that throughout the nulling process, the dc bias for the
baseband inputs remains at 500 mV. When no offset is applied,
VIOPP = VIOPN = 500 mV, or
VIOPP VIOPN = VIOS = 0 V
When an offset of +VIOS is applied to the I-channel inputs,
VIOPP = 500 mV + VIOS/2, and
VIOPN = 500 mV VIOS/2, such that
VIOPP VIOPN = VIOS
The same applies to the Q channel inputs.
It is often desirable to perform a one-time carrier null calibra-
tion. This is usually performed at a single frequency. Figure 25
shows how carrier feedthrough varies with LO frequency over a
range of ±50 MHz on either side of a null at 940 MHz.
–90
–85
–80
–75
–70
–65
–60
–55
–50
–45
–40
890
900
910
920
930
940
950
960
970
980
990
06
51
0-
02
6
LO FREQUENCY (MHz)
CARRI
E
R
F
E
DT
H
RO
UG
H
(
d
Bm
)
Figure 25. Carrier Feedthrough vs. Frequency After Nulling at 940 MHz
Sideband Suppression Optimization
Sideband suppression results from relative gain and relative
phase offsets between the I/Q channels and can be suppressed
through adjustments to those two parameters. Figure 26
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)
06
51
0-
02
7
Figure 26. Sideband Suppression vs. Quadrature Phase Error for Various
Quadrature Amplitude Offsets
Figure 26 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 more 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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| ADL5371ACPZ-R7 | 功能描述:IC MOD QUAD 500-1500 MHZ 24LFCSP RoHS:是 類別:RF/IF 和 RFID >> RF 調(diào)制器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:2,500 系列:- 功能:調(diào)制器 LO 頻率:700MHz ~ 2.3GHz RF 頻率:700MHz ~ 2.3GHz P1dB:1dBm 底噪:-148dBm/Hz 輸出功率:-1dBm 電流 - 電源:46mA 電源電壓:2.7 V ~ 3.6 V 測試頻率:1.75GHz 封裝/外殼:28-WFQFN 裸露焊盤 包裝:帶卷 (TR) |
| ADL5371ACPZ-WP | 制造商:Analog Devices 功能描述:QUADRATURE MOD 700MHZ 24LFCSP EP - Waffle Pack |
| ADL5371-EVALZ | 制造商:Analog Devices 功能描述:EVAL BOARD - Bulk |
| ADL5372 | 制造商:AD 制造商全稱:Analog Devices 功能描述:400 MHz to 6 GHz Broadband Quadrature Modulator |
| ADL5372ACPZ-R2 | 制造商:Analog Devices 功能描述:1500 MHZ TO 2500 MHZ QUADRATURE MODULATOR - Tape and Reel |
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