Conversion circuit for converting single input to differential input and system circuit using the same

A conversion circuit for converting a single-ended input to a differential input, wherein the conversion circuit is adapted to a signal converter, and the conversion circuit comprises:

• a first conversion sub-circuit, comprising a plurality of switches and a plurality of capacitors, configured to selectively receive a low voltage or an input voltage, and configured to output a first end input signal to the signal converter;
• and
• a second conversion sub-circuit, comprising a plurality of switches and a plurality of capacitors, and electrically connected to the first conversion sub-circuit via the low voltage, and configured to selectively receive the input voltage or a first supply voltage, and configured to output a second end input signal to the signal converter;
• wherein
• during a first operation period, the first end input signal and the second end input signal are controlled to be the low voltage by the plurality of switches of the first conversion sub-circuit and the second conversion sub-circuit,
• during a second operation period after the first operation period, the plurality of switches of the first conversion sub-circuit and the second conversion sub-circuit are operated to make a total quantity of electric charge of the capacitors of the first conversion sub-circuit zero and make the total quantity of electric charge of the capacitors of the second conversion sub-circuit is controlled be a product of the capacitance value of one of the capacitors of the second conversion sub-circuit and the input voltage, and
• during a third operation period after the second operation period, the plurality of switches of the first conversion sub-circuit and the second conversion sub-circuit are operated to redistribute the charges of the plurality of capacitors of the first conversion sub-circuit to make the first end input signal be 1/N times of an input signal, and redistribute the charges of the plurality of capacitors of the second conversion sub-circuit to make the second end input signal be 1/N times of the difference between the first supply voltage minus the input voltage.

A circuit system, comprising:

• a conversion circuit configured to convert a single-ended input to a differential input, wherein the conversion circuit is adapted to a signal converter, and the conversion circuit comprises:
• a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor, wherein each of the capacitors has a first end and a second end,
• the second end of the first capacitor is electrically connected to the first end of the second capacitor,
• the second end of the second capacitor is electrically connected to the first end of the fourth capacitor,
• the second end of the second capacitor and the first end of the fourth capacitor are electrically connected to a low voltage,
• the second end of the fourth capacitor is electrically connected to the first end of the third capacitor,
• the second end of the first capacitor and the first end of the second capacitor are configured to output a first end input signal to the signal converter, and
• the second end of the fourth capacitor and the first end of the third capacitor are configured to output a second end input signal to the signal converter;
• a first switch, a second switch, a third switch, and a fourth switch, wherein
• the first switch is electrically connected to the second end of the first capacitor and the first end of the second capacitor,
• the second switch is electrically connected to the first end of the first capacitor,
• the third switch is electrically connected to the second end of the fourth capacitor and the first end of the third capacitor, and
• the fourth switch is electrically connected to the second end of the third capacitor;
• wherein
• the first switch is configured to selectively control the second end of the first capacitor and the first end of the second capacitor to receive the low voltage or be floating based on a first switch control signal,
• the third switch is configured to selectively control the second end of the fourth capacitor and the first end of the third capacitor to receive the low voltage or be floating based on the first switch control signal,
• the second switch is configured to selectively control the first end of the first capacitor to receive the low voltage or an input voltage based on a second switch control signal, and
• the fourth switch is configured to selectively control the second end of the third capacitor to receive the input voltage or a first supply voltage based on the second switch control signal;
• a signal converter, electrically connected to the conversion circuit;
• and
• a function circuit, electrically connected to the signal converter.