Optical transmission circuit and optical transmission/reception circuit module

An optical transmission circuit, comprising:

• a light emitting element;
• a differential amplifier circuit to which differential input signals are input to modulate an optical output of the light emitting element, wherein the differential amplifier circuit includes
• a first current source having a first end and a second end, the first end being connected to a first potential source,
• a first transistor having a first source, a first drain, and a first gate, the first source being connected to the second end, one of the differential input signals being supplied to the first gate,
• a second transistor having a second source, a second drain, and a second gate, the second source being connected to the second end, another one of the differential input signals being supplied to the second gate,
• a third transistor having a third source, a third drain, and a third gate, the third gate and the third drain being connected to the first drain, the third source being connected to a second potential source,
• a fourth transistor having a fourth source, a fourth drain, and a fourth gate, the fourth gate and the fourth drain being connected to the second drain, the fourth source being connected to the second potential source,
• a second current source having a third end and a fourth end, the third end being connected to a third potential source, and the fourth end being connected to the second drain, and
• a fifth transistor having a fifth source, a fifth drain, and a fifth gate, the fifth gate being connected to the fourth gate, the fifth source being connected to the second potential source and the fifth drain being connected to the light emitting element;
• and
• a third current source having a fifth end and a sixth end, the fifth end being connected to a fourth potential, and the sixth end being connected to the fifth drain, wherein the light emitting element is connected between the sixth end and the second potential source.