Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Frequency of cyclic current or voltage
Reexamination Certificate
2007-06-04
2008-10-14
Nguyen, Vincent Q. (Department: 2831)
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Frequency of cyclic current or voltage
C370S350000, C327S105000, C327S119000
Reexamination Certificate
active
07436166
ABSTRACT:
The invention is directed to a digital phase detector that comprises a splitter and phase shifter to receive a signal of a device under test and produce a first signal that is substantially identical to the received signal and a second signal that is phase shifted relative to the first signal. A first analog-to-digital channel processes the first signal to produce an in-phase and quadrature signals. The second signal is processed by a second analog-to-digital channel to produce a second set of in-phase and quadrature signals. The two sets of in-phase and quadrature signals are used to determine a phase difference between the signal of the device under test and a local oscillator signal associated with the two analog-to-digital channels. The invention is further directed to a direct digital synthesizer that is capable of use within the digital phase detector and in other applications. The direct digital synthesizer comprises a sine look-up table or calculator that provides a digital signal representative of the amplitude of a sine wave at an angle of 2πkJ/M where J is an integer number of cycles of the sine wave, M is an integer number of sine wave data values that represent J cycles of the sine wave, and k is an integer number having a value in a range extending from 1 to and including M. By appropriately selecting the value of M, certain spur related issues can be avoided. Further, appropriate selection of J and M allows the synthesizer to generate frequencies that are rational fractions of the frequency of a clock applied to the synthesizer.
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Holland & Hart LLP
Kulish, Esq. Christopher J.
Natalini Jeff
Nguyen Vincent Q.
Timing Solutions Corporation
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