Patent ID: 6985009

Claim:
A signal transmission system for bidirectionally sending and receiving a single-ended signal between a first semiconductor integrated circuit device that operates under a first power supply voltage and a second semiconductor integrated circuit device that operates under a second power supply voltage which is lower than said first power supply voltage, comprising: a transmission line having a predetermined characteristic impedance for performing bidirectional signal transmission between said first semiconductor integrated circuit device and said second semiconductor integrated circuit device; a first CTT terminating circuit for being supplied with said first power supply voltage, said first CTT terminating circuit having a resistance value in conformity with said characteristic impedance and disposed on a signal reception end of said first semiconductor integrated circuit device; a second CTT terminating circuit for being supplied with said second power supply voltage, said second CTT terminating circuit having a resistance value in conformity with said characteristic impedance and disposed on a signal reception end of said second semiconductor integrated circuit device; a reference voltage generating circuit for generating reference voltages which serve as a threshold value for determining the voltage of said single-ended signal and supplying the reference voltages respectively to said first semiconductor integrated circuit device and said second semiconductor integrated circuit device; a first driver of push-pull configuration for sending said single-ended signal from said first semiconductor integrated circuit device, said first driver having an on resistance value set such that the reference voltages used in said first semiconductor integrated circuit device and said second semiconductor integrated circuit device are equal to each other; and a second driver of push-pull configuration for sending said single-ended signal from said second semiconductor integrated circuit device, said second driver having an on resistance set such that the reference voltages used in said first semiconductor integrated circuit device and said second semiconductor integrated circuit device are equal to each other.