Ultralow Phase Noise 10-MHz Crystal Oscillators

Area of Science:

• Electrical Engineering
• Physics
• Metrology

Background:

• Precise frequency standards are essential for modern electronic systems, particularly atomic clocks.
• Low phase noise oscillators are critical components in local oscillator chains for high-precision timing applications.

Purpose of the Study:

• To design and implement low phase noise 10-MHz crystal oscillators using stress compensated (SC) cut crystal resonators.
• To evaluate the phase noise performance of these oscillators for use in compact atomic clocks.

Main Methods:

• The design incorporates a low-noise transformer-coupled differential amplifier.
• A spurious resonance rejection filter and an electronically tuned phase shifter were integrated.
• Phase noise measurements were conducted to characterize oscillator performance.

Main Results:

• Phase noise performance achieved was -122 dBc to -123 dBc/Hz at 1-Hz offsets and -148 dBc/Hz at 10-Hz offsets.
• The noise floor of the oscillators is approximately -161 dBc/Hz.
• Phase noise at 1-Hz offset is comparable to previously produced low-noise BVA resonator-based oscillators.

Conclusions:

• The designed 10-MHz SC-cut crystal oscillators offer excellent phase noise performance.
• These oscillators are suitable as reference oscillators for compact atomic clocks and other timing-critical electronic systems.