Matched charge exchange circuit for analog and digital conversion

摘要

The present invention relates to a circuit for converting between an analog input voltage and a corresponding digital representation of the analog input voltage. First, second and third capacitors are used, the first and second capacitors being matched, the third capacitor serving as an accumulator. A first switch is coupled to one end of the first capacitor, and a second switch is coupled between the one end of the first capacitor and one end of the second capacitor. A third switch coupled between the one end of the second capacitor and one end of the third capacitor, with a discharge circuit being coupled between the one end of the third capacitor and an opposite end of the second capacitor. When the third switch is closed the discharge circuit fully discharges the second capacitor onto the third capacitor. The third switch is closed when the analog input voltage is greater than a reference voltage, and wherein the first switch is closed to discharge the first capacitor followed by opening the first switch and closing the second switch to cause charge on the second capacitor to divide equally between the first and second capacitors when the analog input voltage is not greater than the reference voltage.

主权项

1. A circuit for converting between an analog input voltage and a corresponding digital representation of the analog input voltage, the circuit comprising:
first, second and third capacitors, the first and second capacitors being matched, a first switch coupled to one end of the first capacitor, a second switch coupled between the one end of the first capacitor and one end of the second capacitor, a third switch coupled between the one end of the second capacitor and one end of the third capacitor, and a discharge circuit coupled between the one end of the third capacitor and an opposite end of the second capacitor, such that when the third switch is closed the discharge circuit fully discharges the second capacitor onto the third capacitor, wherein the third switch is closed when the analog input voltage is greater than a reference voltage, and wherein the first switch is closed to discharge the first capacitor followed by opening the first switch and closing the second switch to cause charge on the second capacitor to divide equally between the first and second capacitors when the analog input voltage is not greater than the reference voltage.