| 摘要 |
PURPOSE:To use a circuit in a voltage higher than a breakdown voltage, by connecting two MOS transistors in series and by connecting both substrates to the source of one MOS transistor and by applying a voltage higher than the threshold voltage to the gate of the other. CONSTITUTION:A voltage -VP is applied to the plate of a fluorescent display tube 1, and a drain D1 of a MOS transistor (TR)Q1 is connected to this plate, and the source of the TRQ1 is connected to the drain of a MOSTRQ2, and substrates of TRs Q1 and Q2 are connected to the earth through the source of the TRQ2. A voltage higher than the threshold is applied to the gate of the TRQ1, and a voltage lower than the threshold is applied to the gate of the TRQ2 when an input signal does not come. When a voltage higher than the threshold is applied to the gate of the TRQ1. TRs Q1 and Q2 become low-resistance regions together to supply a plate current iP of the display tube 1. When a voltage lower than the threshold is applied to the gate of the TRQ2 the voltage -VP is dividing and applied to both TRs, and the circuit is operated normally even if the voltage VP is higher than the breakdown voltage. |
