Line current reference generator
The invention generally relates to the field of power factor correction and specifically to generation of a reference waveform which is proportional to line voltage and is controllable in amplitude.
1. A line current waveform generator device for use with a switching regulator, comprising:
a timing circuit for generating a first signal indicating the start of a gauging period and a second signal indicating the end of the gauging period; and
a circuit for receiving the first signal, the second signal, and a third signal from an inductor in the switching regulator and for generating an output signal indicating the magnitude of current rise of the inductor over the gauging period.
2. The device of claim 1 , wherein the gauging period is controllable in duration by altering the timing of the second signal.
3. The device of claim 1 , wherein the output signal is a continuous waveform.
4. A device for generating a line current reference waveform, comprising:
a rectifying circuit for receiving and rectifying a line voltage;
an inductor coupled to the rectifying circuit, wherein a rise in current through the inductor is proportional to the line voltage;
a timing circuit for generating a first signal indicating the start of a gauging period and a second signal indicating the end of the gauging period; and
a current waveform generation circuit for receiving the first signal, the second signal, and a third signal from the inductor and for generating an output signal indicating the magnitude of current rise of the inductor over the gauging period.
5. The device of claim 4 , wherein the current waveform generator circuit comprises a first sample and hold circuit for sampling the current through the inductor in response to the first signal.
6. The device of claim 5 , wherein the current waveform generator circuit comprises a second sample and hold circuit for sampling the current through the inductor in response to the second signal.
7. The device of claim 6 , wherein the current waveform generator circuit comprises a subtractor circuit for subtracting an output of the first sample and hold circuit from an output of the second sample and hold circuit.
8. The device of claim 7 , wherein the current waveform generator circuit comprises a third sample and hold circuit for sampling the output of the subtractor circuit.
9. The device of claim 5 , wherein the inductor is coupled to a current sense resistor.
10. The device of claim 9 , wherein the waveform generator comprises an inverting sense amplifier coupled to the current sense resistor.
11. The device of claim 10 , wherein the waveform generator comprises a first sample and hold circuit for sampling the output of the inverting sense amplifier.
12. The device of claim 11 , wherein the waveform generator comprises a second sample and hold circuit for sampling the output of the first sample and hold circuit.
13. The device of claim 12 , wherein the first sample and hold circuit is controlled by a first timer and the second sample and hold circuit is controlled by a control signal.
14. The device of claim 13 , wherein the waveform generator comprises a transistor coupled between the inductor and current sense resistor.
15. The device of claim 4 , wherein a transistor is coupled between the inductor and the current waveform generator circuit.
16. A method of generating a line current reference waveform, comprising:
rectifying, by a rectifier, alternating current (AC) from a line voltage;
turning on a switch within a switching regulator;
generating, by an inductor within the switching regulator, a rise in current, wherein the rise is proportional to the line voltage;
generating, by a timing circuit, a first signal indicating the start of a gauging period and a second signal indicating the end of the gauging period;
generating, by a waveform generator, a line current reference waveform indicating the magnitude of the rise in current of the inductor over the gauging period.
17. A method of generating a line current reference waveform associated with a switching regulator, comprising:
generating, by a timing circuit, a first signal indicating the start of a gauging period and a second signal indicating the end of the gauging period;
generating, by a waveform generator coupled to an inductor in a switching regulator, a line current reference waveform indicating the magnitude of a rise in current of the inductor over the gauging period.
18. The method of claim 17 , further comprising:
setting the gauging period by setting the timing of the second signal.
19. The method of claim 17 , wherein line current reference waveform is a continuous waveform.