EE版 - direct conversion IQ modulator question on IQ imbalance |
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t****s
发帖数: 20 | 1 Yesterday I was asked for a question which I don't understand:
If use CW signal to drive both I/Q paths, how to use spectrum mode to check
IQ imbalance?
Thanks. | a******t
发帖数: 75 | 2 You may try to send a signal which is supposed to be in the image band.
Let's say the signal is at 1G+100MHz while the image should be in 1G-100MHz.
a CW tone with IQ phase will give you a output signal at 1.1GHz with a
power level 0dBm.
Now you shift the switch I Q input, such that I->Q, Q->I. The output signal
will appear at 900MHz, say, -30dBm power.
The modulator has an image rejection 30dB in this case.
Hope this is the answer you want.
check
【在 t****s 的大作中提到】
: Yesterday I was asked for a question which I don't understand:
: If use CW signal to drive both I/Q paths, how to use spectrum mode to check
: IQ imbalance?
: Thanks.
| t****s
发帖数: 20 | 3 Thanks very much. I think that this is what I am looking for.I need do more
homework.
how do you drive I/Q path? use cw tone in image band? would you please
elaborate?
sorry for my slowness.
100MHz.
signal
【在 a******t 的大作中提到】
: You may try to send a signal which is supposed to be in the image band.
: Let's say the signal is at 1G+100MHz while the image should be in 1G-100MHz.
: a CW tone with IQ phase will give you a output signal at 1.1GHz with a
: power level 0dBm.
: Now you shift the switch I Q input, such that I->Q, Q->I. The output signal
: will appear at 900MHz, say, -30dBm power.
: The modulator has an image rejection 30dB in this case.
: Hope this is the answer you want.
:
: check
| a******t
发帖数: 75 | 4 If you use I signal to drive I path and Q singal to drive Q path, it will
give you a output signal at desired signal band.
If you use Q signal to drive I path and I signal to drive Q path, it will
give a signal at image band.
more
【在 t****s 的大作中提到】
: Thanks very much. I think that this is what I am looking for.I need do more
: homework.
: how do you drive I/Q path? use cw tone in image band? would you please
: elaborate?
: sorry for my slowness.
:
: 100MHz.
: signal
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