Dear friends, I am working with stm32f103RBT6 MCU. I have used AMS1117 3.3V regulator both for MCU VDD and also for the VDDA pin. due to noise from GPRS device I need a way to reduce this noise. ADC value is affected about 2% of input value when GPRS is sending or connecting to server. I have a separate power switching regulator for GPRS and have used small signal capacitors as well as ferret beads. I think I should isolate MCU by a DC/DC from power source or use a reference voltage IC for AVDD. Is there any point other than these?
Thank you very much. Surely I have to change the resistor type. I find the right resistor by reviewing such differences.