Glitch free clock switching technology

Glitch Free Clock switching technology

Two clock switching circuits .Glitch Free It is a burr free switching circuit .

In the first case, the frequency of the two clock sources is a multiple , The second is that there is no relationship between the two clock sources , Asynchronous clock .

Here's how to use AND-OR Type a multiplexer logic for simple clock switching .


The following figure is for the multiple relationship between the frequency of two clock sources . Insert a falling edge trigger in the selected path of each clock source D trigger , This ensures that the above situation is avoided , Make sure that when switching clock sources , Even if any clock is at high level , It will not cause the transformation of the output , When switching clock source , This feedback ensures that a clock is completely deselected , Output propagates another clock , To avoid any burrs .

reg     out1;
  reg     out0;
  always @(negedge clk1 or negedge rst_n)begin
      if(rst_n == 1'b0)begin
          out1 <= 0;
      end
      else begin
          o