To provide a digital signal combining circuit having a function to combine two
digital signals converted from two analog signals and a function to compensate
for nonlinearity of two A/D converters upon input of one analog input signal and
to convert the analog input signal to a digital signal with S/N ratio improved
by about 3 dB.
The digital signal combining circuit has a first inversion circuit (3),
a second inversion circuit (4), an A/D converter (ADC1), a third
inversion circuit (6), a fourth inversion circuit (7), another A/D
converter (ADC2), a digital inversion circuit (11) and a digital
mixer circuit (10). When only one analog input signal is converted to a
digital output signal, the analog input signal is inputted into a positive input
of the A/D converter (ADC1), an inverted analog input signal is inputted
into a negative input of the A/D converter (ADC1), the inverted analog input
signal is inputted into a positive input of the other A/D converter (ADC2),
the analog input signal is inputted into a negative input of the other A/D converter
(ADC2), and the digital inversion circuit (11) inverts a digital
output from the other A/D converter (ADC2).
