| 摘要 |
PURPOSE:To extend a range of conversion while maintaining highly accurate conversion, by providing a constant current source in parallel to a D/A converter which is provided within a closed loop of a sequential comparator. CONSTITUTION:The upper 2 bits of a sequential comparison register 6 are connected to a sub-D/A converting circuit DAC8; while the lower 14 bits are connected to a main D/A converting circuit DAC10. The DAC8 absorbs three types of constant current in response to the input data. As a result, the offset voltage is generated at an input resistance Rin to shift the analog voltage which is fed to a comparator 4. Thus the range of conversion is increased. Furthermore, the converting accuracy can be maintained at a high level if the converting range is varied since the multiplication is not applied to the input signal. |
