Appeal No. 2006-2332
Application No. 09/751,610
BACKGROUND
The invention relates to electronic control systems, in particular precision phase
generators for generating multiple phase clocking signals from a single phase clock
signal. Representative claim 20 is reproduced below.
20. A method for generating at least two clock signals displaced from each
other by a predetermined phase shift of 360//2N, where N is a positive integer,
the method comprising:
applying a clock signal to a signal input of a phase lock loop circuit at a
desired clock frequency;
applying a feedback signal to a second input of the phase lock loop circuit;
generating an output signal of the phase lock loop circuit having a
frequency of 2NF0;
coupling the output signal of the phase lock loop circuit to a clock input of
each JK flip-flop of a Johnson counter to provide the feedback signal to the
second input of the phase lock loop circuit having a frequency corresponding to
the frequency of the output signal of the phase lock loop circuit divided by 2N, the
Johnson counter comprising N JK flip-flops including an input JK flip-flop, an
output JK flip-flop, and a plurality of middle JK flip-flops, each JK flip-flop having
a J input, a K input, the clock input, a Q output, and a complemented Q output,
each middle JK flip-flop and the output JK flip-flop having its J input coupled to
the Q output of a preceding JK flip-flop and its K input coupled to the
complemented Q output of the preceding JK flip-flop, the J input of the input JK
flip-flop being coupled to the complemented Q output of the output JK flip-flop,
the K input of the input JK flip-flop being coupled to the Q output of the output JK
flip-flop; and
coupling outputs of the JK flip-flops of the Johnson counter for use as
phase shifted clock outputs.
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