Switched-capacitor amplifier and analog interface circuit for charge coupled element adopting the same

A switched capacitor amplifier, comprising:

• a first capacitor having a first terminal and a second terminal, said first terminal being connected to an input terminal of an operational amplifier;
• a second capacitor having a first terminal and a second terminal, said first terminal being connected to the input terminal of said operational amplifier;
• a first switch which selects either an output terminal of said operational amplifier in an opposite polarity to the input terminal or a signal input terminal to which an input signal is input, and connects the terminal as selected to the second terminal of said first capacitor;
• and
• a second switch which selects either an output terminal of said operational amplifier in a same polarity to the input terminal or the signal input terminal, and connect the terminal as selected to the second terminal of said second capacitor.

An analog interface circuit for a charge-coupled element, comprising:

• a correlated double sampling circuit for carrying out a correlated double sampling with respect to an analog signal as input from a charge coupled element;
• an amplifier circuit for amplifying an output signal from said correlated double sampling circuit;
• an analog-digital converter for outputting an output from said amplifier circuit into a digital signal;
• and
• a digital-analog converter for compensating the output signal from said analog-digital converter with a black level compensating signal, and converting the output signal as compensated into an analog signal, and feeding back the resulting signal into an input of said amplifier circuit,
• wherein said amplifier circuit is a switched capacitor amplifier which includes:
• a first capacitor having a first terminal and a second terminal, said first terminal being connected to a first connection point;
• a second capacitor having a first terminal and a second terminal, said first terminal being connected to said first connection point;
• and
• control means which stores charges according to an input signal as input to each of said first capacitor and said second capacitor in a sampling phase, and varies a potential of the second terminal of said first capacitor and a potential of the second terminal of said second capacitor in opposite directions as a differential output while maintaining the charges at said first connection point.

An analog interface circuit for a charge-coupled element, comprising:

• a correlated double sampling circuit for carrying out a correlated double sampling with respect to an analog signal as input from a charge coupled element;
• an amplifier circuit for amplifying an output signal from said correlated double sampling circuit;
• an analog-digital converter for outputting an output from said amplifier circuit into a digital signal;
• and
• a digital-analog converter for compensating the output signal from said analog-digital converter with a black level compensating signal, and converting the output signal as compensated into an analog signal, and feeding back the resulting signal into an input of said amplifier circuit,
• wherein said amplifier circuit is a switched capacitor amplifier which includes:
• a first capacitor having a first terminal and a second terminal, said first terminal being connected to an input terminal of an operational amplifier;
• a second capacitor having a first terminal and a second terminal, said first terminal being connected to the input terminal of said operational amplifier;
• a first switch which selects either an output terminal of said operational amplifier in an opposite polarity to the input terminal or a signal input terminal to which an input signal is input, and connects the terminal as selected to the second terminal of said first capacitor;
• and
• a second switch which selects either an output terminal of said operational amplifier in a same polarity to the input terminal or the signal input terminal, and connect the terminal as selected to the second terminal of said second capacitor.