Electronic Components Datasheet Search
  English  ▼

Delete All
ON OFF
ALLDATASHEET.COM

X  

Preview PDF Download HTML

ADL5593 Datasheet(PDF) 5 Page - Analog Devices

Part No. ADL5593
Description  Correcting Imperfections in IQ Modulators to Improve RF Signal Fidelity
Download  8 Pages
Scroll/Zoom Zoom In 100% Zoom Out
Maker  AD [Analog Devices]
Homepage  http://www.analog.com
Logo 

ADL5593 Datasheet(HTML) 5 Page - Analog Devices

   
Zoom Inzoom in Zoom Outzoom out
 5 / 8 page
background image
Application Note
AN-1039
Rev. 0 | Page 5 of 8
The second alternative presented previously is to perform
factory calibration. To do this, the popular single sideband
spectrum can be used as a simple but valuable diagnosis
tool during factory calibration. To create a single sideband
spectrum, the I and Q inputs are driven by low frequency
(typically 1 MHz) sine and cosine signals, that is, the base-
band signals are in quadrature. Figure 3 shows the spectrum
that results when these baseband signals are mixed with the LO.
The primary components of the single sideband spectrum are:
Lower sideband: If the IQ modulator has no imperfections,
this is the only spectral component observed, the result of
multiplication and summing of the baseband sine and
cosine signals with the two in-quadrature LO signals.
Undesired upper sideband: This undesired component
results from gain and phase imbalances between the I and
Q signal paths along with LO quadrature imbalance.
Undesired LO leakage: As discussed earlier, the LO leakage
results from I and Q offsets and/or parasitic leakage of the
LO directly to the IQ modulator’s output.
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
CENTER 899.9334MHz
333kHz/
SPAN 3.33MHz
Figure 3. Single Sideband Spectrum
Figure 4 shows a plot that can be used to relate sideband
suppression to I/Q gain mismatch and quadrature mismatch.
From the plot, it can be noted that a quadrature phase error of
1°, coupled with an I/Q gain mismatch of 0.5 dB, results in
−30 dB of sideband suppression. It is notable in this example
that improving the quadrature phase mismatch has no effect
on the sideband suppression unless the gain mismatch is also
improved.
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
PHASE ERROR (Degrees)
Figure 4. Plot Showing the Relationship Between Modulator Errors and
Sideband Suppression
By using a directional coupler and a power splitter (as shown
in Figure 1), it is quite simple to add an auxiliary output to
the transmitter that can be used during factory calibration. A
spectrum analyzer is connected to this port. Another alternative
would be to connect the spectrum analyzer at the antenna
connector (after the signal has been adequately attenuated).


Html Pages

1  2  3  4  5  6  7  8 


Datasheet Download




Link URL




Privacy Policy
ALLDATASHEET.COM
Does ALLDATASHEET help your business so far?  [ DONATE ]  

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   Alldatasheet API   |   Link Exchange   |   Manufacturer List
All Rights Reserved© Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn