Digitally adjustable phase shifting circuit
First Claim
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1. Apparatus for producing an alternating signal with a controllable phase shift, comprising in combination:
- means producing a periodic signal having a given period;
divider means responsive to said periodic signal for producing a first digital signal changing as a function of said given period and manifested as a plurality of M bits;
means for storing a value indicative of the phase of said alternating signal and for producing, in accordance with said value, a second digital signal manifested as a plurality of N bits comprising M higher order bits and N-M lower order bits and having a control terminal receptive of a control signal for changing said value, where, N≧
M;
means responsive to said first digital signal and second digital signal for adding ones of said M bits of said first digital signal with corresponding ones of said higher orders bits of said N bits to produce a most significant bit (MSB) and lower order bits;
means responsive to said added bits and lower order ones of said N bits for producing an analog alternating signal corresponding to the value of said added and lower order bits; and
means coupled to said means for storing a value for producing a control signal to change said stored value to thereby change the phase of said alternating signal.
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Abstract
A counter produces, as a function of time, an M bit count of cycles of a periodic signal. A storage device stores a changeable value represented by N bits comprising M higher order bits and N-M lower order bits. An adder produces M bits corresponding to the sum of M counter bits and M higher order bits. A digital-to-analog converter produces an alternating signal corresponding to the value of the M summed bits and N-M lower order bits where the phase of the alternating signal relative to an arbitrary reference signal corresponds to the value stored in the storage device.
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Citations
6 Claims
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1. Apparatus for producing an alternating signal with a controllable phase shift, comprising in combination:
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means producing a periodic signal having a given period; divider means responsive to said periodic signal for producing a first digital signal changing as a function of said given period and manifested as a plurality of M bits; means for storing a value indicative of the phase of said alternating signal and for producing, in accordance with said value, a second digital signal manifested as a plurality of N bits comprising M higher order bits and N-M lower order bits and having a control terminal receptive of a control signal for changing said value, where, N≧
M;means responsive to said first digital signal and second digital signal for adding ones of said M bits of said first digital signal with corresponding ones of said higher orders bits of said N bits to produce a most significant bit (MSB) and lower order bits; means responsive to said added bits and lower order ones of said N bits for producing an analog alternating signal corresponding to the value of said added and lower order bits; and means coupled to said means for storing a value for producing a control signal to change said stored value to thereby change the phase of said alternating signal. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification