A/D Converter with bit extension capability using wired-OR outputs

Claim 2

An integrated A/D converter comprising: (1) comparator means for comparing a plurality of different reference voltages individually to an analog input signal and for producing a plurality of output signals as a result of said comparisons; (2) code converter means connected to said comparator means for converting the plural output signals of said comparator means into digital signals of plural bits; (3) critical detecting means for comparing a critical reference voltage having a level outside of the range of said plural reference voltages with the analog input signal and for producing a detection output at a predetermined level in case said analog input signal exceeds said critical reference voltage; (4) control means responsive to external control for selectively forcibly controlling the levels of said digital signals of the plural bits to a selected level in case said detected output of said critical detecting means reaches said predetermined level; (5) first output means for feeding out said digital signals of the plural bits of said code converter means to the plural output terminals of an integrated circuit; and (6) second output means for feeding out the detected output of said critical detecting means to another output terminal of said integrated circuit, wherein said control means includes a control input terminal which is provided as an external terminal of said integrated circuit and means for inhibiting the forced control operation by impressing a control signal upon the control input terminal of said control means.

Claim 3

An integrated A/D converter comprising: (1) comparator means for comparing a plurality of different reference voltages and an analog input signal; (2) code converter means connected to said comparator means for converting the plural output signals of said comparator means into digital signals of plural bits; (3) critical detecting means for comparing the critical reference voltage having a level outside of the range of said plural reference voltages with the analog input signal thereby to feed out a detection output at a predetermined level in case said analog input signal exceeds said critical reference voltage; (4) control means responsive to external control for selectively forcibly controlling the levels of said digital signals of the plural bits to a selected level in case said detected output of said critical detecting means reaches said predetermined level; (5) first output means for feeding out said digital signals of the plural bits of said code converter means to the plural output terminals of an integrated circuit; and (6) second output means for feeding out the detected output of said critical detecting means to another output terminal of said integrated circuit, wherein said control means includes a control input terminal which is provided as an external terminal of said integrated circuit and means for inhibiting the forced control operation by impressing a control signal upon the control input terminal of said control means; wherein said comparator means comprises a plurality of comparator stages each including first and second transistors differentially connected; means for connecting the bases of said first transistors in each stage in common to receive an analog input signal; and means for connecting the bases of said second transistors in each stage to receive a respective one of a plurality of successively-increasing levels of reference voltage, the collector of the second transistors of the (n-x)th stage and the collector of the first transistor of the nth stage being commonly connected, where n and x are non-zero integers and (n+1) equal the number of comparator stages; and load means for connecting the collectors of said first and second transistors in said plurality of comparator stages to a source of supply voltage.

Claim 4

An integrated A/D converter comprising: (1) comparator means for comparing a plurality of different reference voltages and an analog input signal; (2) code converter means connected to said comparator means for converting the plural output signals of said comparator means into digital signals of plural bits; (3) critical detecting means for comparing the critical reference voltage having a level outside of the range of said plural reference voltages with the analog input signal thereby to feed out a detection output at a predetermined level in case said analog input signal exceeds said critical reference voltage; (4) control means responsive to external control for selectively forcibly controlling the levels of said digital signals of the plural bits to a selected level in case said detected output of said critical detecting means reaches said predetermined level; (5) first output means for feeding out said digital signals of the plural bits of said code converter means to the plural output terminals of an integrated circuit; and (6) second output means for feeding out the detected output of said critical detecting means to another output terminal of said integrated circuit, wherein said control means includes a control input terminal which is provided as an external terminal of said integrated circuit and means for inhibiting the forced control operation by impressing a control signal upon the control input terminal of said control means; wherein said comparator means comprises a plurality of comparator stages each including first and second transistors differentially connected; means for connecting the bases of said first transistors in each stage in common to receive an analog input signal; and means for connecting the bases of said second transistors in each stage to receive a respective one of a plurality of successively-increasing levels of reference voltage, the collector of the second transistors of the (n-x)th stage and the collector of the first transistor of the nth stage being commonly connected, where n and x are non-zero integers and (n+1) equal the number of comparator stages; and load means for connecting the collectors of said first and second transistors in said plurality of comparator stages to a source of supply voltage.

Claim 5

An integrated A/D converter according to claim 1, wherein said comparator means includes: (1) a first input terminal forming an external terminal of said integrated circuit; (2) a second input terminal forming an external terminal of said integrated circuit; (3) a plurality of voltage dividing resistors connected in series between said first input terminal and said second input terminal for generating said plural reference voltages at the common connecting points thereamong; and (4) a third input terminal forming an external terminal of said integrated circuit for receipt of said analog input signal.

Claim 6

An A/D converting system comprising: (1) first and second converter circuits each comprising comparator means for comparing a plurality of different reference voltages and an analog input signal, including a plurality of voltage dividing resistors connected in series between first and second terminals for generating said plural reference voltages and a third terminal for receipt of said analog input signal; code converter means for converting the plural output signals of said comparator means into digital signals of plural bits; critical detecting means for comparing the critical reference voltage having a level outside of the range of said plural reference voltages with the analog input signal thereby to feed out a detection output at a predetermined level in case said analog input signal exceeds said critical reference voltage; control means for forcibly controlling the levels of said digital signals of the plural bits in case said detected output of said critical detecting means reaches said predetermined level; first output means for feeding out said digital signals of the plural bits of said code converter means to plural output terminals; and second output means for feeding out the detected output of said critical detecting means to another output terminal, said first converter circuit being formed in a first integrated circuit and said second converter circuit being formed in a second integrated circuit; (2) means for connecting said first terminal of said first converter circuit with a first potential point; (3) means for connecting said second terminal of said first converter circuit with said first terminal of said second converter circuit; (4) means for connecting said second terminal of said second converter circuit with a second potential point; (5) means for impressing an analog signal upon said third terminal of said first converter circuit and upon said third terminal of said second converter circuit; and (6) means for commonly connecting said plural output terminals of said first converter circuit and said plural output terminals of said second converter circuit.

Claim 7

An A/D converting system comprising: (1) first and second converter circuits each comprising comparator means for comparing a plurality of different reference voltages and an analog input signal, including a plurality of voltage dividing resistors connected in series between first and second terminals for generating said plural reference voltages and a third terminal for receipt of said analog input signal; code converter means for converting the plural output signals of said comparator means into digital signals of plural bits; critical detecting means for comparing the critical reference voltage having a level outside of the range of said plural reference voltages with the analog input signal thereby to feed out a detection output at a predetermined level in case said analog input signal exceeds said critical reference voltage; control means for forcibly controlling the levels of said digital signals of the plural bits in case said detected output of said critical detecting means reaches said predetermined level; first output means for feeding out said digital signals of the plural bits of said code converter means to plural output terminals; and second output means for feeding out the detected output of said critical detecting means to another output terminal, said first converter circuit being formed in a first integrated circuit and said second converter circuit being formed in a second integrated circuit; (2) means for connecting said first terminal of said first converter circuit with a first potential point; (3) means for connecting said second terminal of said first converter circuit with said first terminal of said second converter circuit; (4) means for connecting said second terminal of said second converter circuit with a second potential point; (5) means for impressing an analog signal upon said third terminal of said first converter circuit and upon said third terminal of said second converter circuit; and (6) means for commonly connecting said plural output terminals of said first converter circuit and said plural output terminals of said second converter circuit.

Claim 8

An A/D converting system according to claim 4, wherein said control means in each of said first and second converter circuits includes a control input terminal which is provided as the external terminal of said integrated circuit out of said integrated circuit so that the forced control operation is prohibited by impressing a control signal upon the control input terminal of said control means.

Claim 9

An A/D converting system according to claim 5, further comprising: means for feeding said control signal to a selected one of said control input terminals of said first and second converter circuits.

Claim 10

An A/D converting system according to claim 5, further comprising: means for connecting said another output terminal of said first converter circuit and said control input terminal of said second converter circuit.