| 摘要 |
PURPOSE:To constitute a D/A converter with only resistances having the same value and to facilitate controlling the production process and designing the layout while keeping a high precision by using resistances having the same value in a symmetrical ladder type resistance ladder circuit and weighting a current conducted to them with a specific resistance ladder. CONSTITUTION:Currents conducted to ladder resistances R are weighted in accordance with a power series of 1/2 by base resistances R which make emitter potentials of transistors TRs Q1-Qn, which constitute current mirrors, different from one another by DELTAV. As the result, resistances having the same value can be used as the resistances of the ladder circuit. Currents may be weighted not by causing voltage drop by base resistances but by changing emitter areas.
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