Method of suppressing electromagnetic interference emission
First Claim
1. A method of regulating a power converter having a switching circuit, the method comprising:
- a. selectively drawing power from a power supply according to a control signal used to drive the switching circuit;
b. generating a low frequency modulation signal when the switching circuit draws power from the power supply, and discontinuing generation of the low frequency modulation signal when the switching circuit is not drawing power from the power supply; and
c. applying the low frequency modulation signal so as to generate a modulated control signal that is modulated according to the low frequency modulation signal.
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Accused Products
Abstract
An EMI emission suppressing system, apparatus and method that enables the EMI produced by high frequency switching of a switching circuit to be suppressed via the transfer of the higher order harmonic emissions to a frequency range below the standard EMI bandwidth of less than 150 KHz by applying low frequency modulation or jitter into the feedback of a switching signal of the switching circuit. The EMI suppression is achieved with minimal added ripple on the output signal of the switching circuit by using discontinuous modulations in the form of only applying the low frequency modulation when the switch or higher order harmonic producing element of the switching circuit is accessing, or drawing power from, the main power supply.
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Citations
27 Claims
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1. A method of regulating a power converter having a switching circuit, the method comprising:
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a. selectively drawing power from a power supply according to a control signal used to drive the switching circuit; b. generating a low frequency modulation signal when the switching circuit draws power from the power supply, and discontinuing generation of the low frequency modulation signal when the switching circuit is not drawing power from the power supply; and c. applying the low frequency modulation signal so as to generate a modulated control signal that is modulated according to the low frequency modulation signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of regulating a power converter having a switching circuit, the method comprising:
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a. selectively drawing power from a power supply according to a control signal used to drive the switching circuit; b. generating a low frequency modulation signal; and c. applying the low frequency modulation signal when the switching circuit draws power from the power supply so as to generate a modulated control signal that is modulated according to the low frequency modulation signal, and discontinuing application of the low frequency modulation signal when the switching circuit is not drawing power from the power supply. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method of regulating a power converter having a switching circuit, the method comprising:
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a. injecting a low frequency modulation signal into a summation circuit configured to output an error signal; b. modulating the error signal of the summation circuit using the low frequency modulation signal when the switching circuit is drawing power from a power supply, and discontinuing modulation of the error signal using the low frequency modulation signal when the switching circuit is not drawing power from the power supply; and c. using the modulated error signal to substantially reduce harmonic distribution in a switching frequency of the switching circuit. - View Dependent Claims (22, 23, 24, 25, 26, 27)
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Specification