In order to make the analog-digital converter can be directly used for various battery capacity measurement system without voltage conversion chip
the modulator in the Delta -Sigma ADC is designed in second-order single-loop structure with 0.35μm CMOS technology
and its measurement scope of application range 1.4 V to 4.2 V with 12bits resolution at the 5V power supply.The ADC with this modulator has the advantages of wide measurement scope of range to batteries and low cost.