Output Circuit for Semiconductor Device, Semiconductor Device Having Output Circuit, and Method of Adjusting Characteristics of Output Circuit

Abstract

To decrease the circuit scale necessary for the calibration of the output circuit and to decrease the time required for the calibration operation. The invention includes a first output buffer and a second output buffer that are connected to a data pin, and a calibration circuit that is connected to a calibration pin. The first output buffer and the second output buffer include plural unit buffers. The unit buffers have mutually the same circuit structures. With this arrangement, the impedances of the first output buffer and the second output buffer can be set in common, based on the calibration operation using the calibration circuit. Consequently, both the circuit scale necessary for the calibration operation and the time required for the calibration operation can be decreased.

What is claimed is: 
     
         1 . A semiconductor device having an output circuit, the output circuit comprising:
 a first output buffer that is connected to a data pin, and is activated at least at a data output time;   a second output buffer that is connected to the data pin, and is activated at least at an ODT operation time; and   a calibration circuit that is connected to a calibration pin for controlling impedances of the first output buffer and the second output buffer in common.