Author Topic: DAC input to IQ modulator  (Read 3001 times)

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Offline srscricketTopic starter

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DAC input to IQ modulator
« on: February 05, 2014, 07:25:26 am »
I have two differential outputs from a dac that needs to go in to the four pins of the IQ modulator. I was trying to avoid going to another layer and it seems I cant. I was wondering if anyone had any ideas on separating them in to layers. The picture is what I have so far.
 

Offline Rerouter

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Re: DAC input to IQ modulator
« Reply #1 on: February 05, 2014, 07:31:10 am »
you haven't said what your grid size is, but i would guess using a 1206 package resistor as a jumper if you want to avoid going interrupting the other layer (a zoomed out image would equally be nice)
 

Offline srscricketTopic starter

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Re: DAC input to IQ modulator
« Reply #2 on: February 05, 2014, 07:45:32 am »
The grid size is 20 mil. The picture was zoomed in because that was all I had down, most of the other pins will be the outputs from an fpga. Thanks for the reply.

-edit- now with attachment
 

Offline fcb

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Re: DAC input to IQ modulator
« Reply #3 on: February 05, 2014, 12:00:37 pm »
It won't matter a jot if it's low frequency, but will if it's high frequency.  You should give a bit more information about the IC's and the frequency.

There maybe other options (perhaps their are other DAC outputs available, perhaps you can flip a bit in the DAC configuration and sort out polarity, etc..).

All else being equal, you need to make sure the traces are the same length and have the same characteristic impedance (so each trace has the same number of vias etc...).
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Offline w2aew

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Re: DAC input to IQ modulator
« Reply #4 on: February 06, 2014, 03:04:13 am »
It won't matter a jot if it's low frequency, but will if it's high frequency.  You should give a bit more information about the IC's and the frequency.

There maybe other options (perhaps their are other DAC outputs available, perhaps you can flip a bit in the DAC configuration and sort out polarity, etc..).

All else being equal, you need to make sure the traces are the same length and have the same characteristic impedance (so each trace has the same number of vias etc...).

Can you invert the data on I or Q in the DAC, thus being able to swap the diff pairs?  Maybe that will help your layout.
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