D/A converter and delta-sigma D/A converter
AssigneeAsahi Kasei Microsystems Co., Ltd.
InventorIchiro Fujimori
Life of this patent
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Abstract
A D/A converter for converting a given digital signal into an analog signal includes a plurality of capacitors (C1, C2 . . . , Ci) for storing an electric charge corresponding to a predetermined reference voltage (Vr+or Vr-). The reference voltage is selected depending on the digital signal during a period when a clock .phi.1 is at a high level. A switch selection (SUG1-SUGi, SB) is used to connect each of the plurality of capacitors between an input terminal and an output terminal of an operational amplifier 100 during a period when a clock +2 is at a high level.
Claims26
A D/A converter for converting a multi-bit digital signal into an analog signal, the D/A converter comprising:
- a plurality of capacitors for storing, during a first time period, reference voltages corresponding with respective bits of the multi-bit digital signal, said reference voltages being delivered to respective ones of each of the plurality of capacitors;
- and
- a switch for connecting each of the plurality of capacitors in parallel to one another between an input terminal and an output terminal of an operational amplifier during a second period.
A D/A converter for converting a multi-bit digital signal into an analog signal, the D/A converter comprising:
- a first plurality of capacitors for storing, during a first time period, reference voltages corresponding with respective bits of the multi-bit digital signal, said reference voltages being delivered to respective ones of the plurality of capacitors;
- a first switch section for connecting each of the first plurality of capacitors in parallel to one another between an inverting input terminal and a non-inverting output terminal of an operational amplifier during a second period;
- a second plurality of capacitors for storing, during the first time period, reference voltages corresponding with respective bits of the multi-bit digital signal, said reference voltages being delivered to respective ones of the plurality of capacitors;
- and
- a second switch section for connecting each of the second plurality of capacitors in parallel to one another between a non-inverting input terminal and an inverting output terminal of the operational amplifier during the second period.
A delta-sigma D/A converter for sampling a multi-bit digital signal at a predetermined sampling frequency and converting the multi-bit digital signal into an analog signal, comprising:
- a digital interpolation filter coupled to convert the digital signal into a second digital signal at a frequency greater than the sampling frequency by interpolating the digital signal;
- a delta-sigma modulator coupled to convert the second digital signal into a third digital signal of a lower bit number by noise shaping the second digital signal;
- and
- a D/A converter coupled to perform a digital-to-analog conversion upon the third digital signal, wherein the D/A converter includes
- a plurality of capacitors for selectively storing, during a first time period, an electric charge corresponding to a word grouping of bits within the multi-bit digital signal delivered across a bus to respective ones of the plurality of capacitors, and
- a switch section for connecting each of the plurality of capacitors in parallel to one another between an input terminal and an output terminal of an operational amplifier during a second period;
- and
- dynamic element matching coupled between the delta-sigma modulator and the D/A converter.
A delta-sigma D/A converter for sampling a multi-bit digital signal at a predetermined sampling frequency and converting the multi-bit digital signal into an analog signal, comprising:
- a digital interpolation filter coupled to convert the digital signal into a second digital signal at a frequency greater than the sampling frequency by interpolating the digital signal;
- a delta-sigma modulator coupled to convert the second digital signal into a third digital signal of a lower bit number by noise shaping the second digital signal;
- and
- a D/A converter for performing a digital-to-analog conversion upon the third digital signal, wherein the D/A converter includes
- a first plurality of capacitors for selectively storing, during a first time period, an electric charge corresponding to a word grouping of bits within the multi-bit digital signal delivered across a bus to respective ones of the first plurality of capacitors,
- a first switch section for connecting each of the first plurality of capacitors in parallel to one another between an inverting input terminal and a non-inverting output terminal of an operational amplifier during a second period,
- a second plurality of capacitors for selectively storing, during the first time period, an electric charge corresponding to a word grouping of within the multi-bit digital signal delivered across a bus to respective ones of the second plurality of capacitors, and
- a second switch section for connecting each of the second plurality of capacitors in parallel to one another between a non-inverting input terminal and an inverting output terminal of the operational amplifier during the second period;
- and
- dynamic element matching coupled between the delta-sigma modulator and the D/A converter.
A method for converting a multi-bit digital signal into an analog signal, comprising:
- supplying reference voltages corresponding to respective bits of the multi-bit digital signal across separate conductors to respective ones of a plurality of capacitors during a first time period;
- and
- connecting each of the plurality of capacitors in parallel between an input terminal and an output terminal of an operational amplifier during a second time period.
A method for converting a multi-bit digital signal into an analog signal, comprising:
- supplying reference voltages corresponding to respective bits of the multi-bit digital signal across separate conductors to respective ones of a first plurality of capacitors during a first time period;
- and
- connecting each of the first plurality of capacitors in parallel between an inverting input terminal and a non-inverting output terminal of an operational amplifier during a second time period.
Dependencies are inferred from the claim text.