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

• Main Author: Okamoto, Kouji
• Format: Patent
• Language: English
• Published: 08.06.2004

The present invention relates to a signal processing device and a D/A converter, and more particularly to a D/A conversion technique used in a signal processing device including an analog-digital mixed loop having a digital section and an analog section for converging a loop output to a target value through the analog-digital mixed loop. A D/A converter in an analog-digital mixed loop is realized with a reduced circuit area without sacrificing the resolution. A bit modulation section modulates an m-bit digital control signal, which is output from a digital section, into an n-bit (n<m) intermediate digital signal whose temporal average precision is substantially m bits. A D/A conversion section converts the intermediate digital signal into an intermediate analog signal having a range corresponding to m bits. Then, by the smoothing operation through an analog filter, the intermediate analog signal is output as an analog control signal that has an m-bit precision as that of the original signal. In this way, it is possible to reduce the bit width for the internal operation and thus to reduce the circuit area without sacrificing the resolution of a D/A converter.