SEMICONDUCTOR DEVICE

PURPOSE:To increase the switching speed of a logic circuit by using an impurity layer as an emitter resistor for a transistor and bringing a control terminal for the resistance value of the resistor to the same potential as the base of the transistor. CONSTITUTION:An N type epitaxial layer 2 is grown on a P type semiconductor substrate 1, a P type impurity is diffused into the layer 2 to form a diffusion resistor 3, and an N type impurity layer 4 is formed in the resistor 3. The resistance value of a resistor using electrodes 6, 8 as electrodes can be controlled by the potential of the layer 4 connected to an electrode 7 through such formation. When the base potential VB of a transistor is connected to the terminal 7 in the constitution, the terminal 7 rises up to a high potential level when potential VB rises up to a high level, and the resistance value of the resistor 2 is increased relatively. Accordingly, a power supply flowing through the resistor 2 is reduced, a charge to an additional capacitance 3 is quickened in response to the reduction, and the speed of rise of potential V0 is increased. When potential VB lowers up to a low level, on the other hand, the resistance value of the resistor 2 reduces, and the speed of drop of potential V0 also slows down.