6/23/2023 0 Comments Quartzcrystal characteristics hamTemperature stability of quartz and MEMS. MEMS oscillators also have higher phase noise for high offsets (12 kHz to 20 MHz) because they use a low-Q LC oscillator for the PLL circuit.įigure 6: Quartz Oscillator and MEMS Oscillator Stability Plotĥ) Frequency Over Temperature Characteristics Phase noise at low offsets is critical for wireless communications and can cause some errors in optical communications. At 10 Hz, the quartz oscillator has 36 dB better phase noise than the MEMS oscillator. MEMS oscillators have higher phase noise for low offsets because the silicon resonator has poor “Q” or Quality factor as compared to quartz. Laboratory measurements also demonstrate that the quartz oscillators have much better phase noise than the MEMS oscillators. The ECS part was selected for the comparison because it is a “standard oscillator” used in many applications and manufactured in large volume. This is nearly eight times better than the MEMS oscillator. When testing the quartz-based crystal oscillator across the SONET bandwidth of 12 kHz to 20 MHz we achieve a 0.18 pS rms jitter. When measuring the jitter of the MEMS oscillator from 12 kHz to 20 MHz, we get 1.5 pS rms jitter measured. One with a MEMS-based resonator and one with a quartz based resonator. We choose off the shelf comparably priced oscillators. As a result, the MEMS oscillator draws 6.09 mA and the standard quartz oscillator draws about 3.16 mA, that’s two times more current needed by the MEMS to only achieve comparable jitter and phase noise levels to the quartz oscillator.įigure 3: Oscillator Start-Up Characteristics 40 MHz The PLL and LCVCO raise the total power consumption. Quartz-based oscillators have much lower power consumption because they have the advantage of a fundamental or harmonic oscillation and a simple circuit structure.īy contrast, MEMS-based oscillators consume more power because they have more circuitry.
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