Signal processing device having a D/A converter with a reduced circuit area without sacrificing the resolution

A signal processing device including a loop having a digital section for processing a digital signal and an analog section for processing an analog signal for converging a loop output to a target value through the loop, the signal processing device comprising a D/A converter for converting an m-bit (m is a positive integer) digital control signal received from the digital section into an analog control signal having substantially the same precision as that of the m-bit digital control signal so as to output the analog control signal to the analog section, the D/A converter including:

• a bit modulation section for producing, from lower (m−n) bit/bits (n is a positive integer:
• n<m) of the m-bit digital control signal, a 1-bit modulation bit whose temporal average precision is substantially the same as an (m−n)-bit precision;
• a D/A conversion section for converting upper n bit/bits of the m-bit digital control signal into a first intermediate analog signal having a range corresponding to m bits;
• a power supply section, which is capable of outputting an analog value corresponding to one bit in the D/A conversion section, and which outputs a second intermediate analog signal in response to the modulation bit as a switching signal;
• an adder for adding together the first and second intermediate analog signals;
• and
• an analog filter for smoothing an output from the adder so as to output the smoothed signal as the analog control signal.

A D/A converter, comprising:

• a bit modulation section for modulating an m-bit (m is a positive integer) digital signal into n-bit (n is a positive integer:
• n<m) intermediate digital signal whose temporal average precision is substantially the same as a precision of the m-bit digital signal;
• a D/A conversion section for converting the n-bit intermediate digital signal into an intermediate analog signal having a range corresponding to m bits;
• and
• an analog filter for smoothing the intermediate analog signal so as to output the smoothed signal as an analog signal whose precision is substantially the same as that of the m-bit digital signal.

A D/A converter, comprising:

• a bit modulation section for producing, from lower (m−n) bit/bits (m and n are each a positive integer:
• n<m) of an m-bit digital signal, a 1-bit modulation bit whose temporal average precision is substantially the same as an (m−n)-bit precision;
• a D/A conversion section for converting upper n bit/bits of the m-bit digital signal into a first intermediate analog signal having a range corresponding to m bits;
• a power supply section, which is capable of outputting an analog value corresponding to one bit in the D/A conversion section, and which outputs a second intermediate analog signal in response to the modulation bit as a switching signal;
• an adder for adding together the first and second intermediate analog signals;
• and
• an analog filter for smoothing an output from the adder so as to output the smoothed signal as an analog signal whose precision is substantially the same as that of the m-bit digital signal.