Digital-to-analog conversion circuit and analog-to-digital conversion device using the circuit

An analog-to-digital conversion device comprising:

• a digital-to-analog conversion circuit for receiving a digital signal group including first and second digital input signal groups and generating an analog voltage corresponding to the digital signal group, said digital-to-analog conversion circuit including;
• a first reference voltage generation circuit for generating a plurality of first reference voltages;
• a plurality of second reference voltage generation circuits for generating a plurality of second reference voltages created by dividing a difference in potential between adjacent two of the first reference voltages;
• a first selective control circuit for, upon receiving a first digital input signal group, selecting one of the first reference voltages and applying the selected one to a specified one of a plurality of signal lines during a first period, and selecting all of second reference voltages generated in one of said plurality of second reference voltage generation circuits and applying all the selected second reference voltages to signal lines other than the specified signal line, respectively, during a second period succeeding the first period;
• and
• a second selective control circuit for, upon receiving a second digital input signal group, applying a voltage of the specified signal line to an analog output terminal during the first period, and applying voltages of the signal lines other than the specified signal line to the analog output terminal during the second period;
• a comparison circuit for comparing an analog voltage to be converted with an analog voltage obtained from the analog output terminal of said digital-to-analog conversion circuit;
• and
• a control circuit for receiving a comparison output signal of said comparison circuit, and generating a digital conversion signal group corresponding to the comparison output signal and generating the digital signal group which is to be supplied to the digital-to-analog conversion circuit,
• wherein said first selective control circuit comprises:
• a first decoder for, upon receiving the first digital input signal group and first and second control input signals, generating a first decoded output signal group when the first control input signal is activated and generating a second decoded output signal group when the second control input signal is activated;
• a plurality of first switching elements each provided between the specified signal line and each of nodes from which the plurality of first reference voltages are generated, and selectively turned on in response to the first decoded output signal group of said first decoder;
• and
• a plurality of second switching elements each provided between each of the signal lines other than the specified signal line and each of nodes from which the plurality of second reference voltages are generated, and selectively turned on in response to the second decoded output signal group of said first decoder, and
• wherein said second selective control circuit comprises:
• a second decoder for, upon receiving the second input digital signal group and the first and second control input signals, generating a first output control signal when the first input control signal is activated and generating a third decoded output signal group corresponding to the second input digital signal group when the second input control signal is activated:
• a third switching element connected between the specified signal line and the analog output terminal and turned on in response to the first output control signal generated from the second decoder;
• and
• a plurality of fourth switching elements connected between each of the signal lines other than the specified signal line and the analog output terminal and selectively turned on in response to the third decoded output signal group generated by the second decoder.

A digital-to-analog conversion circuit comprising:

• a first reference voltage generation circuit for generating a plurality of first reference voltages;
• a plurality of second reference voltage generation circuits for generating a plurality of second reference voltages created by dividing a difference in potential between adjacent two of the first reference voltages;
• a first selective control circuit for selectively connecting a plurality of signal lines to an analog output terminal upon reception of a first digital input signal group;
• and
• a second selective control circuit for selecting one of the second reference voltages generated from said plurality of second reference voltage generation circuits in response to a second digital input signal group, and applying the selected one to a corresponding signal line,
• wherein said first selective control circuit comprises:
• a first decoder for generating a first decoded output signal group upon reception of the first digital input signal group:
• and
• a plurality of first switching elements each provided between the analog output terminal and each of the plurality of signal lines and selectively turned on in response to the first decoded output signal group of said first decoder, and
• wherein said second selective control circuit comprises:
• a second decoder for generating a second decoded output signal group upon reception of second digital input signal group;
• and
• a plurality of second switching elements each provided between each of nodes from which the second reference voltages are generated and a corresponding signal line, and selectively turned on in response to the second decoded output signal group of said second decoder.

An analog-to-digital conversion device comprising:

• a digital-to-analog conversion circuit for receiving a digital signal group including first and second digital input signal groups and generating an analog voltage corresponding to the digital signal group, said digital-to-analog conversion circuit including;
• a first reference voltage generation circuit for generating a plurality of first reference voltages;
• a plurality of second reference voltage generation circuits for generating a plurality of second reference voltages created by dividing a difference in potential between adjacent two of the first reference voltages;
• a first selective control circuit for selectively connecting a plurality of signal lines to an analog output terminal upon reception of a first digital input signal group;
• and
• a second selective control circuit for selecting one of the second reference voltages generated from said plurality of second reference voltage generation circuits in response to a second digital input signal group, and applying the selected one to a corresponding signal line;
• a comparison circuit for comparing an analog voltage to be converted with an analog voltage obtained from the analog output terminal of said digital-to-analog conversion circuit;
• and
• a control circuit for receiving a comparison output signal of said comparison circuit, and generating a digital conversion signal group corresponding to the comparison output signal and generating the digital signal group which is to be supplied to the digital-to-analog conversion circuit,
• wherein said first selective control circuit comprises:
• a first decoder for generating a first decoded output signal group upon reception of the first digital input signal group;
• and
• a plurality of first switching elements each provided between the analog output terminal and each of the plurality of signal lines and selectively turned on in response to the first decoded output signal group of said first decoder, and
• wherein said second selective control circuit comprises:
• a second decoder for generating a second decoded output signal group upon reception of the second distal input signal group;
• and
• a plurality of second switching elements each provided between each of nodes from which the second reference voltages are generated and a corresponding signal line, and selectively turned on in response to the second decoded output signal group of said second decoder.