Signal combining circuit having two A/D converters

A signal combining circuit comprising:

• a first inversion circuit that inverts an analog input signal;
• a second inversion circuit that inverts the analog input signal inverted by said first inversion circuit;
• an A/D converter that inputs output signals from said first and second inversion circuits and converts the signals into digital output signals;
• a third inversion circuit that inverts another analog input signal;
• a fourth inversion circuit that inverts the other analog input signal inverted by said third inversion circuit;
• another A/D converter that inputs output signals from said third and fourth inversion circuits and converts the signals into other digital output signals;
• and a digital mixer circuit that combines said digital output signals from said A/D converter and said other digital output signals from said other A/D converter, wherein said A/D converter and said other A/D converter respectively have a positive input and a negative input, and wherein said signal combining circuit further comprises a digital inversion circuit to be connected to said other A/D converter, further wherein when said A/D converter and said other A/D converter convert only said analog input signal into the digital output signal, said analog input signal is inputted into said positive input of said A/D converter via at least one of said first to fourth inversion circuits, said inverted analog input signal is inputted into said negative input of said A/D converter via at least one of said first to fourth inversion circuits, said inverted analog input signal is inputted into said positive input of said other A/D converter via at least one of said first to fourth inversion circuits, and said analog input signal is inputted into said negative input of said other A/D converter via at least one of said first to fourth inversion circuits, further wherein said digital inversion circuit inverts the digital output from said other A/D converter.