| 摘要 |
PROBLEM TO BE SOLVED: To correct nonlinearity of analog input voltage without performing digital operation.SOLUTION: A signal ratio change circuit 2 outputs, to a power supply line 7, voltage (=Vref+A1*&Dgr;V) obtained by adding first differential voltage proportional to differential voltage &Dgr;V(=analog input voltage Vin-reference voltage Vref) to the reference voltage Vref; and outputs, to a power supply line 8, voltage (=Vref-A2*&Dgr;V) obtained by subtracting second differential voltage proportional to the differential voltage &Dgr;V from the reference voltage Vref, where the absolute value of the second differential voltage differs from that of the first differential voltage. A first pulse circulation circuit 31 is supplied from the power supply line 7 and a ground line 9 with power supply voltage; a second pulse circulation circuit 32 is supplied from the power supply line 8 and a ground line 9 with power supply voltage. A circulation count difference measurement unit 3 outputs a pulse circulation count difference between the pulse circulation circuits 31, 32. A conversion control circuit 4 makes the pulse circulation circuits 31, 32 simultaneously perform circulation operation and outputs, as A/D conversion data, an output value of the circulation count difference measurement unit 3 at the time of outputting a conversion data output processing signal Sa. |
