Miscellaneous active electrical nonlinear devices – circuits – and – Signal converting – shaping – or generating – Synchronizing
Reexamination Certificate
2011-03-22
2011-03-22
Donovan, Lincoln (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Signal converting, shaping, or generating
Synchronizing
Reexamination Certificate
active
07911247
ABSTRACT:
The clock signal supplied to the delta-sigma modulator in a fractional-N phase-locked loop is dithered. In one example, the PLL includes a novel programmable clock dithering circuit. The programmable clock dithering circuit is controllable via a serial bus to dither the phase of the clock signal in a selected one of several ways. If the clock signal is dithered in a first way (pseudo-random phase dithering), then the power of digital noise generated by the delta-sigma modulator is spread over a frequency band, thereby reducing the degree to which the noise interferes with other circuitry. If the clock signal is dithered in a second way (rotational phase dithering), then the power of digital noise is frequency shifted such that the degree to which the noise interferes with the other circuitry is reduced. The programmable clock dithering circuit can be controlled in other ways. For example, dithering can be programmably disabled.
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Gudem Prasad S.
Xu Yang
Zhang Gang
Donovan Lincoln
Qualcomm Incorporated
Rojas Daniel
Xu Jiayu
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