Miscellaneous active electrical nonlinear devices – circuits – and – Signal converting – shaping – or generating – Frequency or repetition rate conversion or control
Reexamination Certificate
2006-07-11
2006-07-11
Callahan, Timothy P. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Signal converting, shaping, or generating
Frequency or repetition rate conversion or control
C327S091000, C327S094000, C327S235000, C327S295000, C327S077000, C327S078000
Reexamination Certificate
active
07075346
ABSTRACT:
A method and circuit for synchronizing an input clock signal with a plurality of internal clock signals in a multiple phase Pulse Width Modulation (PWM) switching power supply without using a Phase Locked Loop (PLL). A period of the input clock signal is measured by using a frequency to voltage converter. A reference capacitor charged by a constant current source is arranged to generate a reference voltage with a slope based on the period of the input clock signal. A change in the reference voltage across the reference capacitor is substantially inversely proportional to a frequency of the input clock. By providing the reference voltage to a sample-and-hold circuit and using an output of the sample-and-hold circuit to feed a comparator, synchronization may be accomplished. Each internal clock signal is generated by different reference capacitor and current source circuit.
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Hariman George A.
Tomiyoshi Kenji
Branch John W.
Callahan Timothy P.
Darby & Darby PC
Luu An T.
National Semiconductor Corporation
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