Patent ID: 7078942

Claim:
A driving apparatus for generating a drive current, comprising: a first square wave generator directed to accomplish timing control of the drive current, the first square wave generator comprising a first comparator, a low frequency sawtooth wave generator, and a timing control signal source, wherein the low frequency sawtooth wave generator is connected to one input of the first comparator, and the timing control signal source is connected to another input of the first comparator; a second square wave generator directed to accomplish amplitude control of the drive current, wherein the second square wave generator comprises a second comparator, a high frequency sawtooth wave generator, a variable amplifier, and an amplitude control signal source, and wherein one input of the variable amplifier is connected to the output of the first square wave generator, another input of the variable amplifier is connected to the amplitude control signal source, an output of the variable amplifier is connected to one input of the second comparator, and the high frequency sawtooth wave generator is connected to another input of the second comparator; a field effect transistor; and a power source; wherein an output of the second square wave generator is connected to a gate of the field effect transistor, a current clamping resistor is provided between a source of the field effect transistor and the power supply, and a drain of the field effect transistor generates the device current to drive a desired load.