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Re: [linrad] Mixer design - comments please
- Subject: Re: [linrad] Mixer design - comments please
- From: Alex Crow <acrow@xxxxxxxxxxxxxxxxxxxx
- Date: Tue, 8 Jul 2003 16:07:02 +0100
On Tuesday 08 July 2003 3:13 pm, Edson Pereira wrote:
> Hi Bob,
> I understand the need for square levels for the multiplexer. For some
> reason I thought that the AD9852 already had a digital I/Q output. I
> reread the datasheet and found that the chip only provides a comparator.
> -- Edson
Why they didn't put in two comparators I'm not sure - it seems silly to have
only one. I guess it's pretty easy to do IQ in DDS though since all you have
to do is shift your address forward in the sine lookup table a bit.
Well, I'm nearly finalised on the mixer design, and I think I'm going to reuse
most of someone else's board for the DDS. I've also ordered one of those
hugely expensive oscillators... I just have to wait 3 months for that so for
a) 50MHz Xtal osc and use the internal PLL to get the 200MHz ref
or b) 50MHz Xtal osc and some conventional transistor doublers.
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