| 摘要 |
PURPOSE:To reduce both the power supply voltage and power consumption of a D/A converter and to facilitate a conversion of the D/A converter into an IC, by keeping the detecting accuracy of current at a fixed level with addition of resistances and switches to the D/A converter. CONSTITUTION:A series circuit of (n) units of current detecting resistances 211- 213 having a prescribed resistance ratio and changeover switches 201-203 is set to a DAC1, current sources 11-13 and changeover switches 40-40 which constitute a D/A converter. The switches 201-203 are switched synchronously with phases phi1-phi7 of a timing signal producing circuit 22. The signal obtained by the voltage drops of resistances 211-213 is amplified by an amplifier 6 and then applied to LPF81-83 connected to changeover switches 91-93 via a phase detecting circuit 7 to be fed back to current sources 11-13. Then the voltage drops of the resistances 211-213 which detect a binary coded load current of high accuracy are set constant while keeping the detecting accuracy at a constant level. Thus both the power supply voltage and power consumption are attained for the D/A converter. This process facilitates a conversion of the D/A converter into an IC. |
