Patent ID: 6985043

Claim:
An atomic oscillator whose resonance frequency derives from atomic transitions, the oscillator comprising: (a) a voltage-controlled oscillator that produces an oscillation signal based on a given control voltage; (b) a radio-frequency (RF) signal synthesizer that produces an RF signal, comprising: a modulator that modulates the oscillation signal with a given low-frequency signal, a phase-locked loop (PLL) that directly produces a first frequency in an atomic resonance frequency band in synchronization with the modulated oscillation signal, the first frequency being an integer multiple of the frequency of the oscillation signal given by said voltage-controlled oscillator, a frequency synthesizer that creates a second frequency by using the oscillation signal as an input clock signal, the second frequency being specified by a frequency control word, and a mixer that mixes the first and second frequencies to produce the RF signal; (c) an atomic resonator in which atoms in an electromagnetic field of the RF signal interact with discharge lamp light passing therethrough, depending on a difference between the RF signal frequency and atomic resonance frequency, said atomic resonator having a sensor that produces a resonance detection signal representing the amount of unabsorbed discharge lamp light; (d) a frequency controller that produces the control voltage by performing synchronous detection on the resonance detection signal; and (e) a frequency setting unit that sets the frequency control word to specify the second frequency of said frequency synthesizer.