Patent ID: 9037003
Filing Date: 2015-05-19
Classification: H04B

Abstract:
1. A signal transmission device for driving a light-emitting element and outputting an optical signal depending on an electric signal, which is a data signal from an electronic device, the signal transmission device comprising: an element driving portion which supplies a driving current to the light-emitting element, wherein the driving current is obtained by superimposing a modulation current on a bias current, the modulation current being dependent on the data signal indicating emitting information of the light-emitting element; a first voltage generation portion which generates a voltage depending on a temperature, wherein the generated voltage will compensate for both high and low temperatures and is derived from a single current source, being inversely proportional to the temperature; a second voltage generation portion which generates a predetermined voltage regardless of the temperature; and a temperature compensation portion which controls the bias current and the modulation current depending on the temperature, wherein the temperature compensation portion reproduces a temperature-current characteristic of the light-emitting element based on the voltage applied from the first voltage generation portion and the voltage applied from the second voltage generation portion, thereby performing current control depending on the temperature.