Abstract: An analog-to-digital conversion device includes quantization circuits and binarization circuits. Each quantization circuit samples an input analog signal at a predetermined period to obtain a sample, quantizes the sample into a (n+1)-valued signal with n (n is an integer of two or more) thresholds, and outputs the quantized value. Each binarization circuit converts the (n+1)-valued quantized value output from the quantization circuit into a binary code.

Abstract: According to this invention, a resonant tunneling transistor includes a first semiconductor layer having an n-type conductivity and serving as a collector layer, a second semiconductor layer having a p-type conductivity and serving as a base layer, a third semiconductor layer having the n-type conductivity and serving as an emitter layer, a fourth semiconductor layer serving as a first barrier layer against either of electrons and holes in the first and second semiconductor layers, and a fifth semiconductor layer serving as a second barrier layer against either of electrons and holes in the second and third semiconductor layers. The first, second, third, fourth, and fifth semiconductor layers are sequentially stacked in an order of the first, fourth, second, fifth, and third semiconductor layers.