Patent ID: 7639038
Filing Date: 2009-12-29
Classification: H04L

Abstract:
1. A semiconductor integrated circuit comprising: a current source circuit coupled between a first node and a first voltage, said first voltage being one of a power supply voltage and a ground voltage; a monitoring resistor part having a plurality of first resistors that are selectively coupled in parallel between the first node and a second voltage said second voltage being the other of the power supply voltage and the ground voltage; a terminating resistor part having a plurality of second resistors that are selectively coupled in parallel between a second node and the second voltage; a comparator circuit configured to compare a voltage of the first node and a reference voltage and to output a comparison result; a control part, including a shift register part receiving the comparison result from the comparator circuit, configured to control the first resistors that are selectively coupled in parallel in the monitoring resistor part by an output of the shift register part in response to the comparison result when making a calibration; and an external terminal coupled to the second node, wherein the control part selectively couples the second resistors in parallel in the terminating resistor part similarly to the first resistors of the monitoring resistor part in response to the comparison result when controlling a resistance of the terminating resistor part, and wherein the control part includes a timing control part configured to output the output of the shift register part to the terminating resistor part in response to an external signal, and the output of the shift register part is constantly output to the monitoring resistor part.