Zero-crossing detector circuit in FPGA

Discussion in 'Embedded Systems and Microcontrollers' started by charko, Aug 18, 2010.

  1. charko

    Thread Starter New Member

    Apr 27, 2010
    Hi everybody!

    I want to know how can i implement zero crossing detector using VHDL in FPGA. So i want to implement a digital constant fractional discriminator. The firt part provide a bipolar signal was implemented but i want to know how i can implement zero crossing detector in vhdl.

    Thank you for your help!
  2. Papabravo


    Feb 24, 2006
    You can't. Zero crossing is essentially an analog function, and VHDL has no concept of continuous analog values. Outside of the FPGA you could implement a window comparator with some hysteresis to indicate the zero crossing event. The DIGITAL output of the comparator can then be routed to the FPGA for further processing.

    You could also have an analog to digital converter with a parallel output bus that would connect to FPGA inputs, but again that's not the same thing as doing it inside the FPGA in VHDL