Analog-digital converter with gain adjustment for high-speed operation
First Claim
Patent Images
1. An analog-digital converter comprising:
- an AD converter circuit converting an input analog signal into a digital value of a predetermined number of bits;
a DA converter circuit converting an output of said AD converter circuit into an analog signal;
a first amplifier circuit provided parallel with said AD converter circuit and amplifying said input analog signal by a predetermined gain;
a subtracter circuit subtracting an output of said DA converter circuit, amplified by a gain practically identical to the gain of said first amplifier circuit, from an output of said first amplifier circuit; and
a second amplifier circuit amplifying an output of said subtracter circuit and feeding the amplified output back to inputs of said AD converter circuit and said first amplifier circuit.
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Abstract
An input analog signal is fed to an amplifier circuit and an AD converter circuit. The AD converter circuit converts the input analog signal into a digital value of a predetermined number of bits, and outputs the digital value to an encoder (not shown) A DA converter circuit converts the digital value of a predetermined number of bits output from the AD converter circuit into an analog signal. The amplifier circuit samples and amplifies the input analog signal by a factor of α (greater than 1). A subtracter circuit subtracts an output of the DA converter circuit amplified by a factor of α from an output of the amplifier circuit.
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Citations
24 Claims
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1. An analog-digital converter comprising:
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an AD converter circuit converting an input analog signal into a digital value of a predetermined number of bits; a DA converter circuit converting an output of said AD converter circuit into an analog signal; a first amplifier circuit provided parallel with said AD converter circuit and amplifying said input analog signal by a predetermined gain; a subtracter circuit subtracting an output of said DA converter circuit, amplified by a gain practically identical to the gain of said first amplifier circuit, from an output of said first amplifier circuit; and a second amplifier circuit amplifying an output of said subtracter circuit and feeding the amplified output back to inputs of said AD converter circuit and said first amplifier circuit. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An analog-digital converter comprising:
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an AD converter circuit converting an input analog signal into a digital value of a predetermined number of bits; a DA converter circuit converting an output of said AD converter circuit into an analog signal; a first amplifier circuit provided parallel with said AD converter circuit and amplifying said input analog signal by a first gain; a subtracter circuit subtracting an output of said DA converter circuit, amplified by a gain practically identical to the gain of said first amplifier circuit, from an output of said first amplifier circuit; and a second amplifier circuit amplifying an output of said subtracter circuit by a second gain and feeding the amplified output back to said AD converter circuit, wherein a total gain, which is a product of said first gain and said second gain, represents a required gain, and said first gain is greater than 1 and equal to or smaller than said second gain. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. An analog-digital converter comprising:
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an AD converter circuit converting an input analog signal into a digital value of a predetermined number of bits; a DA converter circuit converting an output of said AD converter circuit into an analog signal; a first amplifier circuit provided parallel with said AD converter circuit and amplifying said input analog signal by a first gain; a subtracter circuit subtracting an output of said DA converter circuit, amplified by a gain practically identical to the gain of said first amplifier circuit, from an output of said first amplifier circuit; and a second amplifier circuit amplifying an output of said subtracter circuit by a second gain and feeding the amplified output back to said AD converter circuit, wherein a total gain, which is a product of said first gain and said second gain, represents a required gain, and the first gain is set to a value close to said second gain. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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23. An analog-digital converter converting an input analog signal into a digital signal of a plurality of bits in a plurality of stages, comprising a plurality of amplifier circuits, wherein two or more of said amplifier circuits with practically the same gain are differently designed in respect of at least one of a circuit constant and a circuit configuration,
the analog-digital converter further comprising a plurality of stages converting an input analog signal into a digital value of a predetermined number of bits, wherein at least one of said plurality of stages includes two of said plurality of amplifier circuits, a first amplifier circuit of said two amplifier circuits amplifying said input analog signal by a first predetermined gain, and a second amplifier circuit of said two amplifier circuits amplifying, by a second predetermined gain, a difference between an analog signal output from said first amplifier circuit and a signal derived by conversion from a digital value, obtained by analog-to-digital conversion in a stage in which said second amplifier circuit is provided, into an analog signal amplified by practically the same gain as said first predetermined gain, and feeding back the amplified difference to an input of the stage.
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24. An analog-digital converter converting an input analog signal into a digital signal of a plurality of bits in a plurality of stages, comprising a plurality of amplifier circuits, wherein two or more of said amplifier circuits with practically the same gain are differently designed in respect of at least one of a circuit constant and a circuit configuration,
the AD converter according further comprising: -
an AD converter circuit converting an input analog signal into a digital value of a predetermined number of bits, and a DA converter circuit converting an output of said AD converter circuit into an analog signal, wherein a first amplifier circuit of said plurality of amplifier circuits amplifies said input analog signal by a first predetermined gain, and a second amplifier circuit of said plurality of amplifier circuits amplifies, by a second predetermined gain, a difference between an analog signal output from said first amplifier circuit and an analog signal output from said DA converter circuit, amplified by practically the same gain as said first predetermined gain, and outputs the amplified difference to said AD converter circuit and said first amplifier circuit.
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Specification