PLL test board ordered - LNA board started

A project log for Photo-acoustic Spectroscopy

Creating an at home photo-acoustic spectroscopy system

JasMoHJasMoH 12/15/2017 at 00:310 Comments

Test boards and stencils for the PLL subsystem are on order. This includes a CD4046 based design with divide by 64 capability for the ADA2200's clocking requirement. It also can phase shift the output by steps using a digital delay line in the feedback loop. 

The input conditioning logic will track the midpoint of the input clock and use that as the reference for a comparator. This should allow flexible inputs from the "real world".

I've also begun laying out the front-end, which has by far the most stringent layout requirements. Both the transimpedance amplifier (pictured), and the instrumentation amplifier require guard rings for mitigating stray surface charge migration. I have both of them under their own cans.