I have designed a circuit that uses the TI CC1310 microcontroller, and has a daughtboard that has the PIR sensor and amplification circuitry from the from the TIDA-00489
When I look at the output of the amplification circuitry of the amplified PIR signal seems to look sensible. I have a nice stable line that sits at Vcc/2, until I move near the PIR sensor, at which point it goes to either Vcc or GND. All as expected.
This testing was done with my circuit being powered by a CR123A battery, and sat on a grounded anti-static mat. If I remove the grounding from the mat, or move the PCB off of the matt, the signal becomes very noisy. Rather than a nice thin line on the scope, I see a thick line that has ~0.5V thickness.
Additionally, I have an LED on the PCB, and I flash it every 1 second. When this happens, I see a sharp drop in the output signal of my amplifier every 1 second, seemingly corresponding with when my LED comes on.
Can someone please explain the causes of these noise sources to me, and let me know how they can be remedied?