Friday 2 May 2014

Progress in SDR RX

So here's an update on the design of an Arduino Shield SDR RX.

First the AD9850 is no good, as it has not got 50:50 ratio output square waves. I need 50:50 to make my clock generator, which only divides by /2 not /4 of other designs - thus he VFO is half the frequency... and the Si570 is no good as it does not have complementary outputs. But the Si514 does, and this seems a good choice.

Screen Shot 2014 05 02 at 12 27 00

Screen Shot 2014 05 02 at 12 26 33

This is my circuit. The 7474 flip-flops and driven by complementary clock inputs and give quadrature output for the SDR switches (FST3253).

Screen Shot 2014 05 02 at 12 26 38
The complete circuit is this:

Screen Shot 2014 05 02 at 12 27 06