Patent ID: 6307791
Filing Date: 2001-10-23
Classification: G11C

Abstract:
A semiconductor device comprising:an output buffer having transistors connected in parallel for an external driving purpose;a connection terminal connected to an external resistor; andan output impedance controller connected to the connection terminal and the output buffer, for adjusting the impedance of the output buffer in accordance with the external resistor, the output impedance controller having:a first transistor of a first conductivity type connected to the connection terminal;a first level-controller connected to a gate of the first transistor, for controlling the level of the gate of the first transistor to set the connection terminal to a predetermined voltage level;a second transistor of the first conductivity type having a gate connected to the gate of the first transistor and a source connected to a source of the first transistor;a first dummy transistor group connected to the second transistor, including transistors that are of a second conductivity type, are, correspond to the output buffer transistors, and are connected in parallel;a first controller connected to the second transistor and the first dummy transistor group, for controlling the first dummy transistor group to equalize the level of a connection node between the second transistor and the first dummy transistor group with the predetermined voltage level; anda second controller for controlling the output buffer transistors according to the control carried out by the first controller.