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PDF AD8341 Data sheet ( Hoja de datos )
| Número de pieza | AD8341 | |
| Descripción | 1.5GHz to 2.4GHz RF Vector Modulator | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
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Data Sheet
FEATURES
Cartesian amplitude and phase modulation
1.5 GHz to 2.4 GHz frequency range
Continuous magnitude control of −4.5 dB to −34.5 dB
Continuous phase control of 0° to 360°
Output third-order intercept 17.5 dBm
Output 1 dB compression point 8.5 dBm
Output noise floor −150.5 dBm/Hz @ full gain
Adjustable modulation bandwidth up to 230 MHz
Fast output power disable
4.75 V to 5.25 V single-supply voltage
APPLICATIONS
RF PA linearization/RF predistortion
Amplitude and phase modulation
Variable attenuators and phase shifters
CDMA2000, WCDMA, GSM/EDGE linear power amplifiers
Smart antennas
GENERAL DESCRIPTION
The AD8341 vector modulator performs arbitrary amplitude
and phase modulation of an RF signal. Since the RF signal path
is linear, the original modulation is preserved. This part can be
used as a general-purpose RF modulator, a variable attenua-
tor/phase shifter, or a remodulator. The amplitude can be
controlled from a maximum of −4.5 dB to less than −34.5 dB,
and the phase can be shifted continuously over the entire 360°
range. For maximum gain, the AD8341 delivers an OP1dB of
8.5 dBm, an OIP3 of 17.5 dBm, and an output noise floor of
−150.5 dBm/Hz, independent of phase. It operates over a
frequency range of 1.5 GHz to 2.4 GHz.
The baseband inputs in Cartesian I and Q format control the
amplitude and phase modulation imposed on the RF input
signal. Both I and Q inputs are dc-coupled with a ±500 mV
differential full-scale range. The maximum modulation band-
width is 230 MHz, which can be reduced by adding external
capacitors to limit the noise bandwidth on the control lines.
1.5 GHz to 2.4 GHz
RF Vector Modulator
AD8341
FUNCTIONAL BLOCK DIAGRAM
RFIP
RFIM
VPRF
QBBP QBBM
90°
VPS2
0°
CMOP
IBBP IBBM
Figure 1.
DSOP
RFOP
RFOM
Both the RF inputs and outputs can be used differentially or
single-ended and must be ac-coupled. The RF input and output
impedances are nominally 50 Ω over the operating frequency
range. The DSOP pin allows the output stage to be disabled
quickly in order to protect subsequent stages from overdrive.
The AD8341 operates off supply voltages from 4.75 V to 5.25 V
while consuming approximately 125 mA.
The AD8341 is fabricated on Analog Devices’ proprietary, high
performance 25 GHz SOI complementary bipolar IC process. It
is available in a 24-lead, Pb-free LFCSP package and operates
over a −40°C to +85°C temperature range. Evaluation boards
are available.
Rev. A
Document Feedback
Information furnished by Analog Devices is believed to be accurate and reliable. However, no re-
sponsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 ©2004–2012 Analog Devices, Inc. All rights reserved.
Technical Support
www.analog.com
1 page  
Data Sheet
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
AD8341
QFLP 1
QFLM 2
QBBP 3
QBBM 4
VPS2 5
VPS2 6
PIN 1
INDICATOR
AD8341
TOP VIEW
(Not to Scale)
18 IFLP
17 IFLM
16 IBBP
15 IBBM
14 VPS2
13 DSOP
NOTES
1. THE EXPOSED PADDLE SHOULD BE SOLDERED TO
A LOW IMPEDANCE GROUND PLANE.
Figure 2. 24-Lead Lead Frame Chip Scale Package (LFCSP)
Table 3. Pin Function Descriptions
Pin No.
Mnemonic
1, 2 QFLP, QFLM
3, 4
5, 6, 14, 19, 24
7, 8, 11, 12, 20, 23
9, 10
13
15, 16
17, 18
QBBP, QBBM
VPS2, VPRF
CMOP, CMRF
RFOP, RFOM
DSOP
IBBM, IBBP
IFLM, IFLP
21, 22
RFIM, RFIP
EP
Function
Q Baseband Input Filter Pins. Connect optional capacitor to reduce Q baseband channel low-pass
corner frequency.
Q Channel Differential Baseband Inputs.
Positive Supply Voltage. 4.75 V − 5.25 V.
Device Common. Connect via lowest possible impedance to external circuit common.
Differential RF Outputs. Must be ac-coupled. Differential impedance 50 Ω nominal.
Output Disable. Pull high to disable output stage.
I Channel Differential Baseband Inputs.
I Baseband Input Filter Pins. Connect optional capacitor to reduce I baseband channel low-pass
corner frequency.
Differential RF Inputs. Must be ac-coupled. Differential impedance 50 Ω nominal.
Exposed Paddle. The exposed paddle should be soldered to a low impedance ground plane.
Rev. A | Page 5 of 20
5 Page 
Data Sheet
I-Q ATTENUATORS AND BASEBAND AMPLIFIERS
The proprietary linear-responding attenuator structure is an
active solution with differential inputs and outputs that offer
excellent linearity, low noise, and greater immunity from mis-
matches than other variable attenuator methods. The gain, in
linear terms, of the I and Q channels is proportional to its control
voltage with a scaling factor designed to be 2/V, i.e., a full-scale
gain setpoint of 1.0 (−4.5 dB) for a VBBI (or a VBBQ) of 500 mV.
The control voltages can be driven differentially or single-ended.
The combination of the baseband amplifiers and attenuators al-
lows for maximum modulation bandwidths in excess of 200
MHz.
OUTPUT AMPLIFIER
The output amplifier accepts the sum of the attenuator outputs
and delivers a differential output signal into the external load.
The output pins must be pulled up to an external supply,
preferably through RF chokes. When the 50 Ω load is taken
differentially, an output P1dB and IP3 of 8.5 dBm and 17.5 dBm
is achieved, respectively, at 1.9 GHz. The output can be taken in
single-ended fashion, albeit at lower performance levels.
NOISE AND DISTORTION
The output noise floor and distortion levels vary with the gain
magnitude but do not vary significantly with the phase. At the
higher gain magnitude setpoints, the OIP3 and the noise floor
vary in direct proportion with the gain. At lower gain magni-
tude setpoints, the noise floor levels off while the OIP3
continues to vary with the gain.
AD8341
GAIN AND PHASE ACCURACY
There are numerous ways to express the accuracy of the
AD8341. Ideally, the gain and phase should precisely follow the
setpoints. Figure 4 illustrates the gain error in dB from a best fit
line, normalized to the gain measured at the gain setpoint = 1.0,
for the different phase setpoints. Figure 6 shows the gain error
in a different form, normalized to the gain measured at phase
setpoint = 0°; the phase setpoint is swept from 0° to 360° for
different gain setpoints. Figure 8 and Figure 22 show analogous
errors for the phase error as a function of gain and phase
setpoints. The accuracy clearly depends on the region of opera-
tion within the vector gain unit circle. Operation very close to
the origin generally results in larger errors as the relative
accuracy of the I and Q vectors degrades.
RF FREQUENCY RANGE
The frequency range on the RF input is limited by the internal
polyphase quadrature phase-splitter. The phase-splitter splits
the incoming RF input into two signals, 90° out of phase, as
previously described in the RF Quadrature Generator section.
This polyphase network has been designed to ensure robust
quadrature accuracy over standard fabrication process
parameter variations for the 1.5 GHz to 2.4 GHz specified RF
frequency range. Using the AD8341 as a single-sideband modu-
lator and measuring the resulting sideband suppression is a
good gauge of how well the quadrature accuracy is maintained
over RF frequency. A typical plot of sideband suppression from
1.1 GHz to 2.7 GHz is shown in Figure 28. The level of sideband
suppression degradation outside the 1.5 GHz to 2.4 GHz speci-
fied range will be subject to manufacturing process variations.
–15
–20
–25
–30
–35
–40
–45
0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 2.5 2.7
FREQUENCY (GHz)
Figure 28. Sideband Suppression vs. Frequency
Rev. A | Page 11 of 20
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet AD8341.PDF ] | |
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