A digital to analog converter

Claim 2

A digital to analog converter comprising, means for adding a predetermined value of a signal to a digital signal to produce a controlled digital signal, means for converting upper bits of said controlled digital signal to a first analog signal, said upper bits being an upper group of two groups into which said controlled digital signal is divided, means for converting lower bits of said controlled digital signal to a second analog signal, said lower bits being a lower group of said two groups, means for attenuating said second analog signal by a predetermined attenuating factor depending on the number of said lower bits to produce an attenuated analog signal, and means for producing an analog signal in accordance with the addition of said first analog signal and attenuated second analog signal.

Claim 3

A digital to analog converter according to claim 1, wherein said means for adding includes a half adder which is connected to an input terminal for the most significant bit of said lower bits, and half adders which are connected to input terminals for all of said upper bits such that a carry signal of said half adder for said lower bits is applied to one of said half adders which is for the least significant bit of said upper bits, carry signals of said half adders are applied to one of said half adders for an upper bit of said upper bits by one bit in turn, whereby an ouput of said half adder of said lower bits and digital signals of input terminals excluding the most significant bit of said lower bits are applied to said means for converting said lower bits, and outputs of said half adders of said upper bits and a carry signal of one of said half adders which is for the most significant bit of said upper bits are applied to said means for converting said upper bits.

Claim 4

A digital to analog converter according to claim 1, wherein said means for adding produces said controlled digital signal, said upper bits of which are increased in the number of bits by one bit, said means for converting said upper bits includes a decoder for decoding said upper bits excluding the most significant bit thereof to produce a first decoded signal, and a digital to analog converting means for producing said first analog signal in accordance with said first decoded signal and most significant bit of said upper bits, and said means for converting said lower bits includes a decoder for decoding said lower bits to produce a second decoded signal, and a digital to analog converting means for producing said second analog signal in accordance with said second decoded signal.

Claim 5

A digital to analog converter according to claim 1, wherein said means for converting said upper bits includes a plurality of current sources equal in the number thereof to said upper bits, said plurality of said current sources being turned on the content of said upper bits and the current amount thereof being changed depending on the position in regard to said upper bits.

Claim 6

A digital analog converter according to claim 1, wherein said means for adding produces said controlled digital signal, said upper bits of which are increased in the number of bits by one bit, said means for converting said upper bits includes a decoder for decoding said upper bits to produce a decoded signal, and a digital to analog converting means for producing said first analog signal in accordance with said decoded signal.