Wideband Digitally Controlled Injection-Locked Oscillator
First Claim
1. A frequency modulator circuit, comprising:
- a frequency oscillator incorporating a tank circuit and operative to generate a resonating waveform;
a delay circuit coupled to said frequency oscillator and operative to generate a delayed version of said resonating waveform;
a feedback loop coupled to said frequency oscillator and said delay circuit, said feedback loop operative to inject said delayed resonating waveform back into said tank circuit; and
wherein said modulator circuit frequency is determined by a duration said resonating waveform is delayed by said delay circuit.
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Abstract
A novel and useful digitally controlled injection-locked RF oscillator with an auxiliary loop. The oscillator is injection locked to a time delayed version of its own resonating voltage (or its second harmonic) and its frequency is modulated by manipulating the phase and amplitude of injected current. The oscillator achieves a narrow modulation tuning range and fine step size of an LC tank based digitally controlled oscillator (DCO). The DCO first gets tuned to its center frequency by means of a conventional switched capacitor array. Frequency modulation is then achieved via a novel method of digitally controlling the phase and amplitude of injected current into the LC tank generated from its own resonating voltage. A very linear deviation from the center frequency is achieved with a much lower gain resulting in a very fine resolution DCO step size and high linearity without needing to resort to oversampled noise shaped dithering.
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Citations
16 Claims
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1. A frequency modulator circuit, comprising:
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a frequency oscillator incorporating a tank circuit and operative to generate a resonating waveform; a delay circuit coupled to said frequency oscillator and operative to generate a delayed version of said resonating waveform; a feedback loop coupled to said frequency oscillator and said delay circuit, said feedback loop operative to inject said delayed resonating waveform back into said tank circuit; and wherein said modulator circuit frequency is determined by a duration said resonating waveform is delayed by said delay circuit. - View Dependent Claims (2, 3, 4)
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5. A method of generating an oscillating signal, comprising:
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generating a resonating waveform utilizing an LC tank circuit; delaying said resonating waveform to generate a delayed version of said resonating waveform therefrom; injecting said delayed version of said resonating waveform into said tank circuit to modify the frequency of said resonating waveform; and wherein the oscillator signal frequency is determined by the time said resonating waveform is delayed. - View Dependent Claims (6, 7, 8)
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9. An oscillator circuit, comprising:
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a digitally controlled oscillator (DCO) incorporating an LC tank circuit and operative to generate a resonating waveform; a phase generator for operative to generate a coarse delayed version of said resonating waveform; a digital phase rotator (DPR) circuit operative to generate a fine delayed version of said resonating waveform by interpolating said coarse delayed version of said resonating waveform; a feedback loop coupled to said digitally controlled oscillator and said digital phase rotator circuit, said feedback loop operative to inject said fine delayed version of said resonating waveform back into said tank circuit; and wherein said oscillator circuit frequency is determined by the duration said resonating waveform is delayed by said phase generator and said digital phase rotator circuit. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification