题解 | #4位数值比较器电路#

最后A<B的结果可以用((A>B)+(A<B))'=Y2'*Y1'得到。

`timescale 1ns/1ns

module comparator_4(
	input		[3:0]       A   	,
	input	   [3:0]		B   	,
 
 	output	 wire		Y2    , //A>B
	output   wire        Y1    , //A=B
    output   wire        Y0      //A<B
);

    //求~B，方便比较A>B
    not (_B3,B[3]);
    not (_B2,B[2]);
    not (_B1,B[1]);
    not (_B0,B[0]);
    
    //每一位比较A>B还是A=B
    and (A3_B3,A[3],_B3);//A[3]>B[3]
    xnor (A3B3,A[3],B[3]);//A[3]=B[3]
    and (A2_B2,A[2],_B2);
    xnor (A2B2,A[2],B[2]);
    and (A1_B1,A[1],_B1);
    xnor (A1B1,A[1],B[1]);   
    and (A0_B0,A[0],_B0);
    xnor (A0B0,A[0],B[0]);  
    
    //Y1,A=B
    and (Y1,A3B3,A2B2,A1B1,A0B0);
    
    //Y2，A>B
    and (Y2_2,A3B3,A2_B2);
    and (Y2_3,A3B3,A2B2,A1_B1);
    and (Y2_4,A3B3,A2B2,A1B1,A0_B0);
    or (Y2,A1_B1,Y2_2,Y2_3,Y2_4);
    
    //Y0=Y2'*Y1'
    not (_Y1,Y1);
    not (_Y2,Y2);
    and (Y0,_Y1,_Y2);

endmodule