| 摘要 |
PURPOSE:To realize a device capable of protecting itself from breakdown in the event of such a trouble as a short circuit in a load by a method wherein a variable resistance element similar in structure to a junction-type field effect transistor is connected in series to the input stage base of a planar type bipolar transistor. CONSTITUTION:A semiconductor substrate 1 that is an N type layer implanted with an impurity in low concentration serves also as the collector region of a planar-type bipolar transistor 2. Together with the transistor 2, a variable resistance element 6 is monolithically formed onthe semiconductor substrate 1, constituting a protecting circuit for the transistor 2. The variable resistance element 6 is constituted of a junction-type field effect transistor (J-FET) section 7 electrically connected to the base region 3 of the transistor 2 and a diode section 8 connected forwardly to the collector region 1 of the transistor 2. The drain electrode 15 of the J-FET section 7 is connected by a lead integrated with the drain electrode 15 to the base electrode 16 of the transistor 2, constituting a junction of the anode region 17 of the diode section 8 and the cathode region that is the collector region 1 of the transistor 2.
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