To obtain an analog encoder decoder by providing a 1st-layer block and an index load device connected between one of type-B output terminals of a layer block and a fixed-potential point.

This device is equipped with a 1st-layer block and index load device. The 1st layer block has two active device, having terminals of three types, a terminal of one type of the active devices is connected to a common point connected to the type-A output lead of the 1st-layer block, and terminals of other types are coupled to the output leads of types B of the layer blocks. The index load device is connected between one of type-B output terminals of layer blocks and the fixed potential point. For example, npn transistors 41 to 43 are shown for a layer block 100, the emitters of the transistors 41 to 43 are all interconnected to form the type-A output lead of the layer block 100, and the collectors are connected to the type-B output lead of the layer block 100.