Patent attributes
A circuit is formed on an SOI. The bias generator is connected to the gates of first and second transistors. In the bias generator, a first variable current source is connected to the power supply circuit via a power supply node. A third transistor is connected between the first variable current source and a ground-voltage source. A gate thereof is connected to the gate of the first transistor. A first operational amplifier controls a gate voltage of the third transistor so that a voltage at a second node between the first variable current source and the third transistor becomes almost equal to a reference-voltage. A first characteristics changer is connected to the gate of the third transistor or a second node, to change at least one loop gain characteristics and phase characteristics of a loop from the first operational amplifier, through the third transistor, to the first variable current source.
