Sc integrator

A switched-capacitor integrator, comprising:

• a first operational amplifier including an inverting input, a non-inverting input, and an output;
• a second operational amplifier including an inverting input, a non-inverting input, and an output;
• a first capacitor configured to sample an input signal;
• a second capacitor configured to store an offset voltage;
• a third capacitor configured to store an offset voltage;
• an integrating capacitor which is connected between the output of the first operational amplifier and the inverting input of the first operational amplifier;
• a first switch which connects the first capacitor selectively to the input signal or ground;
• a second switch which connects the third capacitor selectively to the inverting input of the second operational amplifier or ground;
• wherein the second capacitor is connected between the output of the second operational amplifier and the inverting input of the first operational amplifier in a first phase and is connected to ground in a second phase;
• wherein in the first phase, an offset of the first operational amplifier is stored onto the second capacitor and the third capacitor;
• wherein in the second phase, the second operational amplifier generates a virtual ground potential which is shifted by the offset of the first operational amplifier stored on the second capacitor, and, as a result, the offset of the first operational amplifier is compensated.

A method for integrating an input signal using a switched-capacitor integrator, the switched-capacitor integrator including:

• a first operational amplifier including an inverting input, a non-inverting input, and an output,
• a second operational amplifier including an inverting input, a non-inverting input, and an output,
• a first capacitor configured to sample an input signal,
• a second capacitor configured to store an offset voltage,
• a third capacitor configured to store an offset voltage,
• an integrating capacitor which is connected between the output of the first operational amplifier and the inverting input of the first operational amplifier,
• a first switch which connects the first capacitor selectively to the input signal or ground,
• a second switch which connects the third capacitor selectively to the inverting input of the second operational amplifier or ground,
• wherein the second capacitor is connected between the output of the second operational amplifier and the inverting input of the first operational amplifier in a first phase and is connected to ground in a second phase,
• wherein in the first phase, an offset of the first operational amplifier is stored onto the second capacitor and the third capacitor,
• wherein in the second phase, the second operational amplifier generates a virtual ground potential which is shifted by the offset of the first operational amplifier stored on the second capacitor, and, as a result, the offset of the first operational amplifier is compensated,
• the method comprising the following steps:
• a) charging the first capacitor with a difference between the input signal and the offset of the first operational amplifier in the first phase;
• b) storing the offset of the first operational amplifier on the second capacitor and the third capacitor in the first phase;
• c) generating a virtual ground potential at the inverting input of the first operational amplifier in the second phase, the virtual ground potential being shifted by the offset of the first operational amplifier stored on the second capacitor;
• d) integrating a difference between a charge on the first capacitor in the first phase and a charge on the first capacitor in the second phase on the integrating capacitor.

A method for integrating an input signal using a switched-capacitor integrator, comprising the following steps:

• a) providing a switched-capacitor integrator including a first operational amplifier, a second operational amplifier, a first capacitor, a second capacitor, a third capacitor, and an integrating capacitor;
• b) connecting the first capacitor to the input signal in a first phase;
• c) connecting the second capacitor to an output of the second operational amplifier and an inverting input of the first operational amplifier in the first phase;
• d) grounding an inverting input of the second operational amplifier using the third capacitor, in the first phase;
• e) disconnecting the first capacitor from the input signal and grounding the first capacitor in a second phase;
• f) grounding the second capacitor in the second phase;
• g) connecting the third capacitor to ground in the second phase;
• h) integrating difference of charges on the first capacitor between the first phase and the second phase on the integrating capacitor.