JPS56162537A - Switching circuit with high dielectric strength - Google Patents

Abstract

PURPOSE:To obtain dielectric strength double as high as that of a unit transistor (TR) by applying a reference voltage, which sets the operating point of a circuit, between the source and gate of one TR and by inputting a signal voltage, which controls the conductive resistance of the circuit, to the gate of another TR. CONSTITUTION:The drain of a TR11, the source of a TR12, and the gate and drain of a TR14 are connected together. Further, the source of the TR14, the gate of the TR12, and the drain of a TR13 are connected together; and a reference voltage Vref setting the operating point of a circuit is applied between the source and gate of the TR13, and a signal voltage VIN controlling the conductive resistance of the circuit is inputted to the gate 21 of the TR11 to control the lead-in resistance between the source of TR11 and the drain of the TR12. Then, the threshold level of each TR is denoted as VT, and voltages at a connection point 23 and terminal 24 as a V23 and V24 respectively. In this case, when the Vref is so set that Vref= V23+VIN+VT, the TRs 11 and 12 are equal in on resistance, so V24=2XV23. Consequently, the circuit operates as a switching circuit which has dielectric strength twice that of one unit TR.