Atomic oscillator and manufacturing method of the atomic oscillator
View Patent ↗An atomic oscillator includes an atomic cell in which an atom is enclosed, a magnetic field generation part to apply a magnetic field to the atomic cell, a reference oscillator which is controlled based on an atomic resonance signal outputted from the atomic cell and generates a reference signal, and a fractional N-PLL which receives the reference signal to generate a signal including a resonance frequency of the atom, in which when a maximum digit of the resonance frequency adjustable by the magnetic field generation part is a boundary digit, the fractional N-PLL can adjust at least a digit one digit higher than the boundary digit.
1. An atomic oscillator comprising:
an atomic cell in which an atom is enclosed;
a magnetic field generation part to apply a magnetic field to the atomic cell;
a reference oscillator that is controlled based on an atomic resonance signal outputted from the atomic cell and generates a reference signal; and
a fractional N-PLL that receives the reference signal to generate a signal including a resonance frequency of the atom, wherein
when a maximum digit of the resonance frequency adjustable by the magnetic field generation part is a boundary digit, the fractional N-PLL is operable to adjust the resonance frequency at least a digit that is one digit higher than the boundary digit,
the fractional N-PLL includes an n-bit decimal setting part to determine a decimal part of a frequency division ratio, and
when a bit number of the decimal setting part is n, a phase comparison frequency is f PFD , the resonance frequency is f ΔE , and an adjustable ratio of the magnetic field generation part to the resonance frequeny is R M ,following equation is satisfied
f
PFD
2
n
≤
f
Δ
E
×
R
M
.
2. The atomic oscillator according to claim 1 , wherein the fractional N-PLL includes a decimal setting part of at least 25 bits.
3. The atomic oscillator according to claim 1 , wherein the fractional N-PLL is operable to adjust at least remaining digits of the resonance frequency which are higher than the boundary digit.
4. A manufacturing method of an atomic oscillator including an atomic cell in which an atom is enclosed, a magnetic field generation part as a coil to apply a magnetic field to the atomic cell, a reference oscillator that is controlled based on an atomic resonance signal outputted from the atomic cell and generates a reference signal, and a fractional N-PLL that includes an n-bit decimal setting part to determine a decimal part of a frequency division ratio and receives the reference signal to generate a signal including a resonance frequency of the atom, the method comprising:
determining n of a bit number of the decimal setting part of the fractional N-PLL, wherein when a maximum digit of the resonance frequency adjustable by the magnetic field generation part is a boundary digit, the fractional N-PLL can adjust at least a digit one digit higher than the boundary digit, and when a bit number of the decimal setting part is n, a phase comparison frequency is f PFD , the resonance frequency is f ΔE and an adjustable ratio of the magnetic field generation part to the resonance frequency is R M , following equation is satisfied
f
PFD
2
n
≤
f
Δ
E
×
R
M
.
5. The manufacturing method of the atomic oscillator according to claim 4 , further comprising:
giving an initial value to the n-bit decimal setting part of the fractional N-PLL; and
adjusting the value set in the decimal setting part.
6. The manufacturing method of the atomic oscillator according to claim 4 , further comprising
adjusting the current of the magnetic field generation part.
7. A manufacturing method of an atomic oscillator including an atomic cell in which an atom is enclosed, a magnetic field generation part as a coil to apply a magnetic field to the atomic cell, a reference oscillator that is controlled based on an atomic resonance signal outputted from the atomic cell and generates a reference signal, and a fractional N-PLL that includes an n-bit decimal setting part to determine a decimal part of a frequency division ratio and receives the reference signal to generate a signal including a resonance frequency of the atom, the method comprising:
determining at least one of a number of turns and a current of the magnetic field generation part such that the magnetic field generation part can adjust at least a digit not higher than a boundary digit of the resonance frequency, the boundary digit being a digit one digit lower than a minimum digit of the resonance frequency adjustable by the fractional N-PLL, and when a bit number of the decimal setting part is n, a phase comparison frequency is f PFD , the resonance frequency is f ΔE , and an adjustable ratio of the magnetic field generation part to the resonance frequency is R M , following equation is satisfied
f
PFD
2
n
≤
f
Δ
E
×
R
M
.
8. The manufacturing method of the atomic oscillator according to claim 7 , further comprising:
giving an initial value to the n-bit decimal setting part of the fractional N-PLL; and
adjusting the value set in the decimal setting part.
9. The manufacturing method of the atomic oscillator according to claim 7 , further comprising
adjusting the current of the magnetic field generation part.