Patent ID: 8446139
Filing Date: 2013-05-21
Classification: H03L

Abstract:
1. A current source, comprising: a current control oscillator configured to output an oscillation signal of a frequency dependent on an input current; a comparator configured to compare the oscillation signal with a reference signal; a charge pump configured to output a current dependent on a comparison result by the comparator; a low-pass filter configured to include a smoothing capacitor charged and discharged by an output current of the charge pump; a loop converter configured to be connected to the smoothing capacitor and generate a current dependent on a voltage generated by the smoothing capacitor to supply the current as the input current to the current control oscillator; an output converter configured to be connected to the low-pass filter and generate a current dependent on a voltage generated in the low-pass filter to output the current as an output current; and a plurality of the output converters; a plurality of switches; an output terminal that outputs a current of the current source; and a controller; wherein the plurality of switches are connected to the output terminal, each of the plurality of switches is connected to a respective one of the plurality of the output converters, the plurality of the output converters are connected to the low-pass filter, and the controller is connected to the plurality of switches, and switches a current output from the output terminal by controlling opening and closing of the plurality of switches.