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

Claim 2

A switched capacitor amplifier, comprising: 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.

Claim 3

The switched capacitor amplifier as set forth in claim 1 , wherein: said control means applies the same voltage to said second terminals of said first capacitor and said second capacitor in the sampling phase.

Claim 4

The switched capacitor amplifier as set forth in claim 1 , wherein: a plurality of input signals are provided, and a pair of said first capacitor and said second capacitor is provided corresponding to the input signals respectively.

Claim 5

The switched capacitor amplifier as set forth in claim 1 , further comprising: a third capacitor, a terminal on one side of which being connected to said connection point, wherein in the hold phase, said control means changes a potential of said third capacitor according to an input signal different from input signals into said first capacitor and said second capacitor while maintaining charges at said first connection point.

Claim 6

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.

Claim 7

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.

Claim 8

The switched capacitor amplifier as set forth in claim 5 , wherein: a first input terminal to which one of differential input signals is input, and a second input terminal to which the other of the differential input signals is input are provided as said signal input terminal; and a pair of said first and second switches and said first and second capacitors are provided corresponding to a combination of a first input terminal as the signal input terminal and an inverting input terminal as an input terminal of said operational amplifier, and a combination of a second input terminal as the signal input terminal and a non-inverting input terminal as an input terminal of said operational amplifier.

Claim 9

The switched capacitor amplifier as set forth in claim 5 , wherein: a plurality of signal input terminals are provided corresponding to a plurality of input signals; and a pair of said first and second switches and said first and second capacitors are provided corresponding to the signal input terminal respectively.

Claim 10

The switched capacitor amplifier as set forth in claim 5 , further comprising: a third capacitor having a first terminal connected to an input terminal of said operational amplifier; and a third switch which switches between I) a signal input terminal, to which an input signal different from an input signal, is to be input, is connected to the second terminal of said third capacitor and II) a predetermined reference potential is applied to the second terminal of said third capacitor.

Claim 11

The switched capacitor amplifier as set forth in claim 1 , wherein: either said first capacitor or said second capacitor is a variable capacitance capacitor.

Claim 12

The switched capacitor amplifier as set forth in claim 5 , wherein: either said first capacitor or said second capacitor is a variable capacitance capacitor.

Claim 13

The switched capacitor amplifier as set forth in claim 1 , wherein: either said first capacitor or said second capacitor is a capacitor array, and said capacitor array includes a plurality of capacitors, and a switch for changing an electrostatic capacitor value of said capacitor array by switching each of said capacitors.

Claim 14

The switched capacitor amplifier as set forth in claim 5 , wherein: either said first capacitor or said second capacitor is a capacitor array, and said capacitor array includes a plurality of capacitors, and a switch for changing an electrostatic capacitor value of said capacitor array by switching each of said capacitors.

Claim 15

The switched capacitor amplifier as set forth in claim 2 , wherein: either said first capacitor or said second capacitor is arranged so as to linearly change electrostatic capacitor values with respect to control signals.

Claim 16

The switched capacitor amplifier as set forth in claim 5 , wherein: either said first capacitor or said second capacitor is arranged so as to linearly change electrostatic capacitor values with respect to control signals.

Claim 17

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.

Claim 18

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.

Claim 19

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.

Claim 20

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.