Digital phase shifter
AssigneeLeader Electronics Corporation
InventorKenzo Ikuzawa
Life of this patent
Estimating the term…
Abstract
A digital phase shifter is provided which uses a direct digital synthesizer. The digital phase shifter is provided with a digital phase-shifted waveform signal generator in which a plurality of digital phase-shifted waveform signals having different phase shifts are stored. The generator outputs a digital phase-shifted waveform signal corresponding to a specified phase shift from a phase shift specifying section in synchronism with an oscillation signal from a PLL circuit. The output is converted to an analog form by a D/A convertor to generate a phase-shifted waveform.
Claims15
A digital phase shifter for generating a phase-shifted waveform shifted in phase by a specified phase shift from an input waveform having a predetermined frequency, comprising:
- (a) a PLL circuit including an input terminal for receiving said input waveform in an analog form and a voltage controlled oscillator for generating an oscillation signal, said oscillation signal being phase-locked to said input waveform and having a frequency N times said predetermined frequency, where N is an integer equal to or larger than two;
- (b) phase shift specifying means for generating a phase shift specifying signal representing a specified phase shift;
- (c) digital phase-shifted waveform signal generator means connected to receive said oscillation signal and said phase shift specifying signal and having a plurality of digital phase-shifted waveform signals stored therein, said plurality of digital phase-shifted waveform signals having different phase shifts, said generator means being operative to generate a digital phase-shifted waveform signal having said specified phase shift from said plurality of stored digital phase-shifted waveform signals;
- and
- (d) convertor means connected to receive said generated digital phase-shifted waveform signal for converting said generated digital phase-shifted waveform signal to an analog form to generate said phase-shifted waveform.
A phase shifting method for generating a phase-shifted waveform shifted in phase by a specified phase shift from an input waveform having a predetermined frequency, comprising the steps of:
- (a) receiving said input waveform in an analog form and generating an oscillation signal being phase-locked to said input waveform and having a frequency N times said predetermined frequency, where N is an integer equal to or larger than two;
- (b) generating a phase shift specifying signal representing a specified phase shift;
- (c) generating a digital phase-shifted waveform signal having said specified phase shift from a plurality of predetermined digital phase-shifted waveform signals having different phase shifts;
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- (d) converting said generated digital phase-shifted waveform signal to an analog form in synchronism with said oscillation signal to generate said phase-shifted waveform.
Dependencies are inferred from the claim text.