| 摘要 |
<p>PROBLEM TO BE SOLVED: To stably and sufficiently secure output amplitude while miniaturizing a circuit scale.SOLUTION: An optical modulator driving circuit 1 includes: a boosting circuit 9 for boosting a voltage from a pre-stage power source 11 to be supplied to a pre-stage amplifier circuit 3, and for generating a post-stage power source, and for supplying it to a post-stage amplifier circuit 7; and a bias control circuit 31. The post-stage amplifier circuit 7 includes resistance elements 27A and 27B, cascode transistors 23A and 23B, switching transistors 25A and 25B and a drive current source 29 in a serially connected state between a post-stage power source and a ground, and the bias control circuit 31 sets the cascode transistors 23A and 23B in an off-state after the pre-stage power source is turned on and before the post-stage power source is turned on, and sets the cascode transistors 23A and 23B in an on-state after the post-stage power source is turned on, and then biases the cascode transistors 23A and 23B in a predetermined level synchronously with the on-state of the drive current source 29.</p> |
