SEMICONDUCTOR CIRCUIT, DA CONVERTER, MIXER CIRCUIT, RADIO COMMUNICATION DEVICE, THRESHOLD VOLTAGE ADJUSTING METHOD, TRANSISTOR QUALITY DETERMINING METHOD

PROBLEM TO BE SOLVED: To provide a semiconductor circuit, DA converter, mixer circuit, radio communication device, threshold voltage adjusting method and transistor quality determining method that, after adjusting their characteristics, can prevent their characteristics from changing again by operation.SOLUTION: A semiconductor circuit of an embodiment includes a substrate, a tunnel oxide film, electric charge storage film, block layer, and a plurality of nodes. The substrate is made up of semiconductor on which two diffusion zones that will be any of a source or drain are formed. The tunnel oxide film is formed on a region between the diffusion zones of the substrate. The electric charge storage film is formed on the tunnel oxide film and stores electric charges. The block layer is formed between the electric charge storage film and a gate electrode, and a first oxide film, nitride film and second oxide film are stacked such that the thickness of its layer will be 5 nm or more and 15 nm or less. The plurality of nodes are made to be able to apply voltage from the outside so that the source and drain will be switched, and to be able to detect gate voltage, drain current, and substrate current.