Gradually-appoximant analog-digital converter

Abstract

The invention discloses a gradually-appoximant analog-digital converter. A capacitor array is integrated in the gradually-appoximant analog-digital converter. The gradually-appoximant analog-digital converter is characterized in that a capacitor of the capacitor array comprises three stages: the highest position to the fifth position of the output end of a first digital signal are set as a first stage; the fourth position and the third position are set as the second stage; the second position and the lowest position are set as the third stage, i.e. the capacitor at the seventh position of a first capacitor is selected as unit capacitor; the mth capacitor higher than the seventh position is formed by connecting 2m-7 unit capacitors in parallel; capacitors at the sixth position and the fifth position are respectively formed by connecting two and four unit capacitors in series; the connecting mode of the second stage and the third stage is the same as the connecting mode at the fifth position and the sixth position; various capacitors at various stages are connected in parallel; and three unit capacitors are connected between two adjacent capacitor arrays in series. By improving a structural mode for connecting the capacitor arrays in grade, the invention can effectively reduce the number of capacitors, reduce the capacitor area and improve the match precision, thereby realizing low power consumption, high matching degree, low parasitism and compromise among low area of the analog-digital converter.

Description

technical field [0001] The invention relates to the design of a CMOS integrated circuit, in particular to a circuit design of a successive approximation analog-to-digital converter. By improving the connection structure and mode of its capacitor array, low power consumption, high matching degree, low parasitic and low area can be realized. compromise between. Background technique [0002] In current circuit applications, analog-to-digital conversion has always been one of the main modules of the circuit. Successive approximation analog-to-digital converter is a commonly used low-power analog-to-digital converter. The important part that determines its speed, power consumption, effective bits and other performance and area is the capacitor array part. [0003] In today's technological environment, the continuous development of medical and personal portable wireless transceiver electronic equipment requires batteries to last for a longer time, so digital and analog circuits ...

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Problems solved by technology

figure 2 The connection method of the capacitor array shown (if the unit capacitor is represented by c, then 8c represents the parallel connection of eight capacitors, rather than the simple multiplication of the capacitance value, the following is the same), because the number of capacitors is doubled

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