Patent ID: 7595662

Claim:
A transmission device, which transmits differential signals that are to be transmitted, in the form of current signals via a first output terminal and a second output terminal, comprising: a first switching transistor and a first output transistor which are serially connected between a fixed-voltage terminal that is set to a fixed voltage and said first output terminal; a second switching transistor and a second output transistor which are serially connected between said fixed-voltage terminal and said second output terminal; a first bias transistor and a second bias transistor which are provided in parallel with said first switching transistor and said second switching transistor, respectively, and each of which generates a predetermined bias current; and a second bias circuit which biases the control terminals of said first bias transistor and said second bias transistor at a predetermined second voltage, wherein a pair of the differential signals to be transmitted are input to the control terminals of said first switching transistor and said second switching transistor; wherein the control terminals of said first output transistor and said second output transistor are biased at a predetermined first voltages; wherein said second bias circuit comprises a third transistor, the control terminal of which is connected to the control terminals of said first bias transistor and said second bias transistor such that they share a common control terminal; and wherein a predetermined second bias current is supplied to a path including said third transistor; and wherein the control terminal of said third transistor is connected to a node on a path for the second bias current.