| 摘要 |
PURPOSE: A digital/analog convertor is provided to improve a reliability by providing a resistor part constituted to connect first (2¬M-1) resistors of a coarse stage and a fine stage in serial. CONSTITUTION: A digital/analog converter comprises a decoder, a resistor part of a coarse stage(32), a buffer part(34) and an adder part(35). An output bit number of the decoder is a sum of M and N, wherein M is a bit number of MSB and N is a bit number of LSB. The resistor part of the coarse stage(32) comprises a first resistor(36) string composed of resistors between a reference voltage and a ground and a fine stage(33) being a resistor equivalent to one of the resistors of the first resistor string, wherein the fine stage is coupled to the first resistor string. The buffer part(34) is composed of a first OP amplifier(42) and a second OP amplifier(43), each of which receives outputs from the coarse stage and the fine stage to match the received outputs. The adder part(35) of a non inverse type is composed of a third OP amplifier(44) and second to fifth resistors(45,46,47,48), and adds outputs from the buffer part to output an analog signal corresponding to an input digital signal.
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