Sar adc capable of reducing energy consumption

An SAR ADC capable of reducing energy consumption, comprising:

• a comparator, having a positive input end, a negative input end, and a comparison output end;
• a capacitor circuit, having a first capacitor array and a second capacitor array;
• a pair of sampling switches, having one side coupled to a positive input voltage and a negative input voltage, and the other side coupled to said positive input end and said negative input end of said comparator;
• a logic circuit, having a bit input terminal, N bit output terminals, and a plurality of switch control output terminals, wherein said bit input terminal is coupled to said comparison output end of said comparator, and said switch control output terminals are used for outputting a plurality of switch control signals;
• and
• a voltage selecting circuit, used for executing the following operations according to said switch control signals:
• programming said first capacitor array to provide a first equivalent capacitor having a capacitance of (2m−1)C, and a second equivalent capacitor having a capacitance of (2n−2m+1)C, wherein said first equivalent capacitor has an electrode coupled to said positive input end of said comparator, and the other electrode coupled to a reference voltage or a ground voltage, and said second equivalent capacitor has an electrode coupled to said positive input end of said comparator, and the other electrode coupled to a common mode voltage;
• and
• programming said second capacitor array to provide a fourth equivalent capacitor having a capacitance of (2m−1)C, and a fifth equivalent capacitor having a capacitance of (2n−2m+1)C, wherein said fourth equivalent capacitor has an electrode coupled to said negative input end of said comparator, and the other electrode coupled to said ground voltage or said reference voltage, and said fifth equivalent capacitor has an electrode coupled to said negative input end of said comparator, and the other electrode coupled to said common mode voltage, wherein n, m are positive integers, and m≦2n-1.

An SAR ADC capable of reducing energy consumption, comprising:

• a comparator, having a positive input end, a negative input end, and a comparison output end, wherein said comparison output end is used for providing a bit output;
• and
• a voltage selecting circuit, used for executing the following operations according to a plurality of switch control signals:
• programming a first capacitor array to provide a first equivalent capacitor having a capacitance of (2m−1)C, a second equivalent capacitor having a capacitance of (2n−2m+1)C, and a third equivalent capacitor having a capacitance of (2N-1−2n)C, wherein said first equivalent capacitor has an electrode coupled to said positive input end of said comparator, and the other electrode coupled to a reference voltage or a ground voltage, said second equivalent capacitor has an electrode coupled to said positive input end of said comparator, and the other electrode coupled to a common mode voltage, and said third equivalent capacitor has an electrode coupled to said positive input end of said comparator, and the other electrode kept floating;
• and
• programming a second capacitor array to provide a fourth equivalent capacitor having a capacitance of (2m−1)C, a fifth equivalent capacitor having a capacitance of (2n−2m+1)C, and a sixth equivalent capacitor having a capacitance of (2N-1−2n)C, wherein said fourth equivalent capacitor has an electrode coupled to said negative input end of said comparator, and the other electrode coupled to said ground voltage or said reference voltage, said fifth equivalent capacitor has an electrode coupled to said negative input end of said comparator, and the other electrode coupled to said common mode voltage, and said sixth equivalent capacitor has an electrode coupled to said negative input end of said comparator, and the other electrode kept floating, wherein n, m, N are positive integers, and m≦2n-1, n≦N−1.