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参数资料
| 型号： | AD8347ARUZ |
| 厂商： | ANALOG DEVICES INC |
| 元件分类： | 调制器/解调器 |
| 英文描述： | 800 MHz - 2700 MHz RF/MICROWAVE QUADRAPHASE DEMODULATOR |
| 封装： | MO-153AE, RU-28, TSSOP-28 |
| 文件页数： | 14/28页 |
| 文件大小： | 623K |
| 代理商： | AD8347ARUZ |
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AD8347
Rev. A | Page 21 of 28
The differential output offset voltages of the baseband amplifiers
are typically ±50 mV. This offset voltage results from both input
and output effects.
FILTER DESIGN CONSIDERATIONS
Baseband low-pass or band-pass filtering can be conveniently
performed between the mixer outputs (IMXO and QMXO) and the
input to the baseband amplifiers. Because the output impedance of
the mixer is low (approximately 3 Ω) and the input impedance of
the baseband amplifier is high, it is not practical to design a
filter that is reactively matched to these impedances. An LC
filter can be matched by placing a series resistor at the mixer
output and a shunt resistor (terminated to VVREF) at the input to
the baseband amplifier.
The overall signal-to-noise ratio can be improved by increasing
the VGA gain by driving it with an external voltage or by changing
the setpoint of the AGC circuit. See the Changing the AGC
Setpoint section.
DRIVING CAPACITIVE LOADS
In applications where the baseband amplifiers are driving
unbalanced capacitive loads, place some series resistance between
the amplifier and the capacitive load. For example, for a 10 pF load,
use four 200 Ω series resistors, one in each baseband output.
Because the mixer output drive level is limited to a maximum
current of 1.5 mA, the characteristic impedance of the filter
should be greater than 50 Ω, especially to achieve larger signal
swings.
EXTERNAL BASEBAND AMPLIFICATION
Reduce baseband output offset voltage and noise by bypassing the
internal baseband amplifiers and amplifying the mixer output
signal using a high quality differential amplifier. In the example
shown in
Figure 50 shows the schematic for a 100 Ω, fourth-order elliptic
low-pass filter with a 3 dB cutoff frequency of 20 MHz. Source
and load impedances of approximately 100 Ω ensure that the
filter sees a matched source and load. This also ensures that the
mixer output is driving an overall load of 200 Ω. Note that the
shunt termination resistor is tied to VREF and not to ground.
The frequency response and group delay of this filter are shown
in
Figure 49, two AD8132 differential amplifiers are used
to gain up the mixer output signals by 20 dB. In this example, the
setpoint of the AGC circuit was increased to give an approximate
72 mV p-p input to the external amplifiers. This resulted in final
baseband output signals of 720 mV p-p.
Figure 51 and Figure 52.
The closed-loop bandwidth of the amplifiers in Figure 49 is equal
to approximately 20 MHz. Higher bandwidths are achievable, but
at the cost of lower closed-loop gain. In
IMXO
AD8347
VREF
VDT1
(SEE
TEXT)
L3
1.2
μH
R3
2
Ω
IAIN
R4
2
Ω
C1
4.7pF
C3
8.2pF
C2
150pF
RS
95.3
Ω
L1
0.68
μH
C4
82pF
RL
100
Ω
02675-050
C16
0.1
μF
Figure 49, the output
common-mode levels at Pin 2 (VOCM pin) of the AD8132s are set
by the AD8347’s VREF (approximately 1 V). The output common-
mode levels can also be externally set, using, for example, the
reference voltage from an ADC.
IMXO
AD8347
VREF
10
μF
0.1
μF
QMXO
VDT1
720mV p-p
DIFFERENTIAL
VCM = 1V
R19A
4.99k
Ω
+5V
10
μF
0.1
μF
AD8132
R17A
499
Ω
R18A
499
Ω
R22
20k
Ω
R23
10k
Ω
72mV p-p
VDT2
72mV p-p
R25
20k
Ω
R24
10k
Ω
R17B
499
Ω
4.99k
Ω
R20A
4.99k
Ω
R19B
+5V
–5V
R18B
499
Ω
720mV p-p
DIFFERENTIAL
VCM = 1V
–5V
4.99k
Ω
R20B
10
μF
0.1
μF
10
μF
0.1
μF
AD8132
02675-049
3
8
2
1
6
4
5
3
8
2
1
6
4
5
C16
0.1
μF
Figure 50. Typical Baseband Low-Pass Filter
FREQUENCY (MHz)
–80
1
100
10
ATTE
NTUATION
(dB)
–70
–60
–50
–40
–30
–20
–10
0
02675-051
Figure 49. External Baseband Amplification Example
Figure 51. Frequency Response of 20 MHz Baseband Low-Pass Filter
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AD8347ARUZ | 制造商:Analog Devices 功能描述:IC QUAD DEMODULATOR 0.8-2.7GHZ 28-TSSOP |
| AD8347ARUZ-REEL7 | 功能描述:IC QUADRATURE DEMOD 28-TSSOP TR RoHS:是 类别:RF/IF 和 RFID >> RF 解调器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 功能:解调器 LO 频率:- RF 频率:70MHz ~ 300MHz P1dB:-9dBm 增益:- 噪音数据:6.36dB 电流 - 电源:41.5mA 电源电压:2.7 V 封装/外壳:28-WFQFN 裸露焊盘 供应商设备封装:28-TQFN-EP（5x5） 包装:带卷 (TR) |
| AD8347-EVAL | 制造商:Analog Devices 功能描述:EVALUATION BOARD ((NS)) |
| ad8347-evalz | 制造商:Analog Devices 功能描述:EVAL BD 0.8 GHZ TO 2.7 GHZ DIRECT CONVERSION QUADRATURE DEMO - Bulk |
| AD8348 | 制造商:AD 制造商全称:Analog Devices 功能描述:400 MHz to 6 GHz Broadband Quadrature Modulator |
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