Multi-stage switched capacitor circuit and operation method thereof

An operation method of a switched capacitor circuit, the switched capacitor circuit comprising a first operational stage, a second operational stage and a third operational stage serially connected in sequence, each operational stage operating in a sample phase or a hold phase and generating a detection signal indicating an end of the hold phase, the operation method comprising:

• controlling the second operational stage to operate in the hold phase when the detection signal of the first operational stage indicates the end of the hold phase of the first operational stage, and the detection signal of the third operational stage indicates the end of the hold phase of the third operational stage;
• wherein the first operational stage, the second operational stage and the third operational stage each comprises:
• an input terminal;
• an output terminal;
• a first capacitor having a first end and a second end;
• a second capacitor having a third end and a fourth end;
• a voltage level detection circuit, configured to detect a voltage of the second end of the first capacitor and a voltage of the fourth end of the second capacitor to generate a current source control signal and the detection signal, wherein the detection signal indicates that the voltage of the second end of the first capacitor and the voltage of the fourth end of the second capacitor are substantially the same as a reference voltage;
• a plurality of switches, coupled to the first capacitor, the second capacitor, the input terminal, the output terminal and the voltage level detection circuit;
• and
• a current source, coupled to the output terminal and configured to supply current to the output terminal or to draw current from the output terminal based on the current source control signal.

A switched capacitor circuit comprising a first operational stage, a second operational stage and a third operational stage serially connected in sequence, each operational stage generating a detection signal, the first operational stage, the second operational stage and the third operational stage each comprising:

• an input terminal;
• an output terminal;
• a first capacitor, having a first end and a second end;
• a second capacitor, having a third end and a fourth end;
• a voltage level detection circuit, configured to detect a voltage of the second end of the first capacitor and a voltage of the fourth end of the second capacitor to generate a current source control signal and the detection signal, wherein the detection signal indicates that the voltage of the second end of the first capacitor and the voltage of the fourth end of the second capacitor are substantially the same as a reference voltage;
• a plurality of switches, coupled to the first capacitor, the second capacitor, the input terminal, the output terminal and the voltage level detection circuit;
• a current source, coupled to the output terminal and configured to supply current to the output terminal or to draw current from the output terminal based on the current source control signal;
• and
• a control circuit, coupled to the switches;
• wherein the control circuit of the second operational stage is configured to control the switches based on the detection signal of the first operational stage and/or the detection signal of the third operational stage.