| 摘要 |
PURPOSE:To realize an isolation dielectric strength suited to a limited space and a high temperature-resistance by using junction field effect transistors (TRs) whose gate oxide film thickness is set to 7,000Angstrom -1mum so as to constitute a bridge circuit and providing a resistor to at least one of the TRs. CONSTITUTION:When the input signal of logic 0 is inputted (switch 26 is opened), each source-drain voltage of the junction field effect TRs 21-24 constituting the bridge circuit is made equal and a potential difference between bridge output terminals (a, b) is '0'. An analog signal processing circuit 28 discriminates the state and outputs logic '0'. When the input signal of logic '1' is inputted (switch 26 is closed), a gate potential different from other gate potentials is fed to the TR 21 by a resistor 25, a potential difference is produced between the output terminals of the bridge circuit, the state is discriminated by the signal processing circuit 28 to output the signal of logic '1'. In selecting the gate oxide film of the TRs 21-24 as 7,000Angstrom -1mum, the dielectric strength of nearly 100V is guaranteed.
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